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Published: Sunday, 12 November 2023 20:03

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 Largest Public Companies by Market Cap:

Here is a list of the 5000 largest companies in the world by Market cap. Market cap is what it would cost to buy the company. It's the price of each share multiplied by total number of shares outstanding. The link below also lists companies by their revenue and earnings:

https://companiesmarketcap.com/

It lists 5500 largest companies worldwide, which have a combined market cap of $95T (as of Nov, 2021). Note that there are way more than 5K public companies in the world (USA itself has 5K public companies listed on it's stock exchange). It's hard to find the list of all public companies, and the bottom ones are irrelevant, so we'll just look at these top 5K public companies. About 150 companies have market cap > $100B. Just top 5 companies (<0.1% of world companies on this link) make up >10% of global market cap. Top 50 companies (1% of world companies on this link) make up 30% of global market cap. It's interesting to note that there are only 50 companies in the world which have revenue > $100B and profits > $10B.

Of 5500 companies, 3500 (or 70%) are US firms with total market cap of $50T. So, US stock market comprises 50% of world stock market. China and Japan each have 200 companies in the list with total market cap of $8T and $5T respectively. India is a distant 4th with 500 companies in the list with a total cap of $3T. France, Canada, Germany, UK and Switzerland are next with > $2T in market cap. South Korea, Australia and Hong Kong are other countries with > $1T in market cap. So, top 10 countries comprise > 80% of world's stock market cap. We'll mostly focus on largest global companies, most of which happen to be US companies.

UPDATE:

• July 2024: The site lists 9000 companies worldwide with total market cap of $105T.
  • China Market cap is ~$6T with ~300 companies. It's down from $8T in 2021 due to fall in stock prices.
  • India Market cap has moved up to $4.7T from $4T in just 3 months time due to huge surge in stock prices. It has replaced Japan and on way to replace China. There are ~600 companies in the list now.
  • Japan Market cap is ~$4.6T with ~350 companies. It's down from $5T in 2021 due to fall in stock prices.
• Apr 2024: The site lists 8500 companies worldwide with total market cap of $100T. India's Market cap has moved up to $4T from $3T due to huge surge in stock prices.

These are largest companies in each country (as of Dec 2023):

1. USA: Largest US companies are tech companies: Apple, Microsft ($3T each), Google, Amazon ($2T each), Nvidia, Tesla and Facebook ($1T each) comprise more than 30% of the whole US market cap.
2. China: Only 35 Chinese Companies are over $35B, lead by Tencent, Kweichow Moutai (sells high end Moutai liquor) => both worth $300B each,  PetroChina, ICBC, Agricultural Bank of China, China Mobile Bank of China, China Construction Bank (each with market cap b/w $150B-$250B). Alibaba which used to be the most valuable company at $800B is now only worth $200B.
3. India:
4. Japan:
    

Market segments: There are many segments of USA markets, where these companies operate. Even though I say USA market, but these companies operate globally, and may encompass multiple market segments. The companies shown below are not necessarily headquartered in USA, and may be non USA companies with large revenue base. These are some of the segments with large market cap:

1. Technology: These include both hardware and software companies. The biggest players here are Apple, Amazon, Microsoft, google, Facebook, Tesla, Nvidia, paypal, netflix, Adobe, Intel, Cisco, Oracle, Broadcom, Texas Instruments, etc all of which have Market cap > $100B as of Aug, 2020. Just top 5 tech companies have market cap of $10T or about 1/5th the total US market cap (as of 2023). In 2009 at market bottom, the total US stock market was worth $7T. Now just top 3 tech companies are worth more than that. Time flies fast !!

• Hardware: Intel used to be the biggest semiconductor company, followed by TI since 1980's. However, as of Dec 2023, Intel and TI are each worth $150B only. These are the biggest ones:
  • CPU/GPU chips: Nvidia, Intel, AMD => Nvidia mostly sells GPU (graphics processing unit). With data mining in full craze, they turned from $5B company to almost $1T company in < 10 years. Intel and AMD make x86 CPU (Central processing unit). AMD also makes discrete GPU like Nvidia, so AMD's fortunes have swelled as well with data mining mania. It's valued at $150B as of 2022, while Intel is valued lower than that at $100B.
  • Fabs: TSMC, SMIC, UMC, Gobal Foundaries => Fabrication company which takes orders for chips from all fabless companies (they don't design any chips), The 500 pound gorilla here is TSMC which is $500B copany located in Taiwan. The only US company here is Global Foundaries with market cap of $30, similar to that of SMIC which is a taiwanese company. Samsung also fabricates chips for other companies in addition to it's own chips.
  • Fab Equipments: ASML, Applied Materials (AMAT): AMAT make equipments to be used in fabs. ASML makes photolithographing equipments to be used in Fabs. AMAT used to be bigger than ASML in 2000's, as AMAT made almost all semiconductor equipment, while ASML was just concentrated in Photo Lithography. But with photolithography becoming so much more important with single digit nm designs (2nm - 10nm), ASML have become much bigger than AMAT in just the last few years.  
  • CAD Tools: Cadence, Synopsys => They make software tools for designing chips (not really hardware companies). These are the only 2 big players in CAD tools, and keep buying smaller players. Their tools are used universally at all hardware companies.
  • Analog chips, Custom ASICs, Wireless: Qualcomm, Broadcom, TI, Analog devices, NXP, Infineon, ON semic, Marvell, Renesas => They make thousands of small chips (mostly analog) and ASIC that go into everything. Qualcomm and Broadcom are more into digital side, while others are mostly on anlog side. Qualcomm is an exception where apart from producing it's own chips, it also sells licenses for it's wireless CDMA tech. It has diversified outside of CDMA wireless, and now makes popular snapdragon processors and other phone chips, modems, etc. All these companies also make custom ASIC that are digital chips that go in a specific application, as well as embedded microcontrollers. There is a huge list of companies here, as the barrier to enter is small, especially for custom ASICs. 
  • Memory chips: Micron, Hynix, Sandisk => they make mostly memory chips (DRAM), SDcard, etc.
  • Tech Products: Apple, Samsung, Dell, HP => They mostly buy chips (or make their own for some important ones as Apple has started making it's own chips), assemble them to make hardware products. However, they also invest in their software to be used in their hardware. Apple is the biggest tech company, and considered both a hardware and software company. Samsung designs and fabricates chips too, in addition to building final products. Dell is mostly an assembler of chips, and doesn't design or fabricate it's chips. Apple and Samsung are big in phones, while Dell and HP are big in computers. Even though by number of units sold, Dell and HP are the largest companies for PC, market cap wise they are just about $30B or so, implying just 1% of the market cap of Apple which is at $3T. Samsung's market cap is $300B which is also much smaller than Apple.
  • EV companies: Tesla, Lucid, Rivian, Nio: All are EV (electric vehicle) auto companies, but are treated as tech companies, because they are all in autonomous vehicles which are hot. Nio is a chinese company. All of these companies get their chips from other companies, but also end up having their own chip design in house. Tesla has grown from $20B market cap in 2012 to $1T market cap in 2021. Other EV companies also are valued very highly at $100B or more.
• Software: Microsoft has always been the biggest software company, and still remains at the top spot, even though new comers are closing in.
  • Software Development: Microsoft, Google, Adobe, Oracle, SAP, Vmware, Salesforce, Intuit, Zoom, IBM: They make software primarily to be used by other companies, though most companies are moving into making their own hardware too. IBM used to be a hardware and software company. Now they have broken themselves into 2 companies, with parent company IBM mostly out of IT. IBM used to be the number one tech company in research since 1900's, but now it's just a very small irrelevant player in tech. Microsoft and Google are valued very highly at over $1T each.
  • IT service: Accenture, TCS, Infosys, HCL, Wipro: These are mostly providing IT service providers. They cater to IT needs of big/medium sized companies mostly located in western world. These companies provide lower cost to their clients in managing day to day IT activities.
  • E-commerce: Amazon, shopify, ebay, wayfair: These are websites or apps that make money by selling consumer products (anything as clothes, electronics, home products, kids stuff, etc) directly or by acting as middle man. Amazon is the biggest of these valued at $1T as of 2022. Others are valued at < $50B.
  • Social media: Facebook, snap, pinterest, twitter: These are social networking companies to entertain people. They are valued very highly, with Facebook itself growing from $100B company in 2012 to $500B in 2022.
  • Services: AirBnb, Uber, doordash : They mostly provide services (instead of products) by acting as middleman, via an app or website. AirBnb provides lodging, Uber provides local transportation, while Doordash provides local food delivery. They are all valued at about $100B or so.

2. Drug/Pharma: These are companies that make drugs or medicines. Pfizer, Merck, Eli Lily, Bristol Meyers Squib, Abbott, AbbVie (formed from spinoff of Abbott in 2012), Moderna, are biggest players here. Merck and Pfizer have stayed around market cap of $200B for a long time. Drug companies pay some of the largest dividend yields in US stock market.

3. Banks: 4 largest banks in USA are Chase, Bank of America, Citi and Wells Fargo. Banks used to be the biggest US companies, but now with tech companies on rise, they are not even in top 10. But everyone uses banks, and govt decides how much money they make (by controlling interest rates and feeding them free money), so they are guaranteed to be top money makers. In all other countries, banks are amongst the top companies by market cap. Morgan Stanly, Goldman Sachs, American Express, Charles Schwab, CM bank, Royal Bank of Canada are other big banks, credit card companies  or brokerage firms. Most big credit card companies or brokerage firms also have banking arm, which allows them to get close to interest free money from Govt.

4. Oil: These are oil/gas companies. Historically, these have been the companies with largest market cap, since oil consumption is more than 3% of GDP, so these companies were only the ones, that could make large revenues. Only with such large revenues was it possible to generate income, that could place them at the top. There is nothing besides gas that gets bought and consumed on a daily basis. Largest companies here are Saudi Aramco (Saudi Arabia), Exxon Mobil, Chevron, Shell, PetroChina, Gazprom (Russia), PetroChina, Conoco Philips and BP . Saudi Aramco used to be the largest company by market of $2T for a long time until Apple bethroned it. Now only 3 of oil companies are in the list of 100 largest companies in the world. However, everyone consumes oil everyday (like food), so they are going to be large players, until we run out of gas.

5. Retailers: These are retail companies that have large brick and mortar stores, and sell everyday items. Biggest retailers are Walmart, Kroger, Costco, Target, Home Depot, Lowes. They combined are worth over $1T (as of 2020). Amazon is also a retailer though it's included in tech companies. Most of the companies with highest revenues are retailers, as they sell a lot of stuff. However, they do make less profit, so their market cap is not that high as those of tech companies. Usually their after tax profits are < 5% of their revenues.

• General Retailers (sell everything for consumers) => Walmart, Costco, Kroger
• Home Improvement Stores: Home Depot, Lowes
• Pharmacy Retailers: Walgreens, CVS
• Apparel Retailers:

6. Consumer product Makers: These make all kinds of consumer products. Procter & Gamble, and Johnson & Johnson are 2 largest companies here. Nike is the only brand that has maintained above $100B in market cap selling shoes !! L'Oreal, is another company that has a high market cap.

7. Auto: Since 100 million cars are being sold every year, it's no wonder Auto companies are amongst companies with large yearly revenues. Market caps are not very high, since margins are pretty low in cars. Many of them have > $50B in market cap. Apart from EV companies shown in Tech category, we have Toyota, General Motors, Volkswagon, Ford, Ferrari, BMW, Honda, Hyundai, etc which are traditional auto companies. BYD is a chinese company which was mostly in rechargeable batteries for most of it's life, but now is all in EV vehicles. It has >50% revenue from auto, 40% from phone parts, and 10% from rechargeable batteries. It has market cap of $150B, right behind Toyota with market cap of $250B (and Tesla with market cap of $1T) as of Nov 2021.

8. Misc: I've included all other companies over here.

• Drink companies: Coca Cola and Pepsi have remained over $100B (> $200B as of 2023) companies for long time. Coke has revenue of $50B, Pepsi of $100B, but both make net profit of $10B (as of 2023), and both have almost same market cap. That says a lot about how profitable they are selling colored carbonated water !! StarBucks is also included as a drink company as it sells coffee. It's also > $100B just selling old vanilla coffee :) It has revenue of about $40B with profits of $4B (as of 2023).
• Restaurant chain:  These are fast food chains as well as formal dining restaurants. Majority of the stores are in USA and account for bulk of sales.
  
  • Mcdonald's (MCD) is the only restaurant chain to have > $100B (> $200B as of 2023) in market cap. On revenue of $25B, it makes profit of $7B (as of 2023). That's very high margin of 30%. This is because almost 99% of their stores are franchise, so their revenue is from those franchise fees, royalty, etc. Their only cost is the cost of advertisements, corportae offices, etc. MCD has 40K restaurants of which 15K are in US.
  • Chipotle debuted in 2008 (was bought by McDonalds while it was still in it's infancy, almost unknown to the world) and stock went 50X in 15 years, commanding a market cap of $50B as of 2023, behind McDonalds. On revenue of $10B, it makes profit of $1B (as of 2023). The stock behaved like a hot startup even though it's food menu is nothing out of ordinary.
  • Yum! Brands (owns KFC, Pizza Hut, Taco Bell, which were spunoff from Pepsi in 1997): It's market cap is only $35B asof 2023. It had revenues of $7B, and profit of $1.5B. Again most of it's stores are franchise similar to MCD
  • Darden Restaurants (owns multiple fine dining and casual dining restaurants as Ruth Chris's Steak house, Olive Garden, etc. Red Lobster was spunoff in 2014. These were all under General Mills which spun them off as a separate company in 1995):
  • Dominos's Pizza rounds up top 5 in USA.
• Telecommunication providers: AT&T, Verizon, Tmobile USA and Comcast also regularly command > $100B in market cap.
• Media: media companies as Disney, Netflix are > $100B companies.
• Payment Processor: Here we have Paypal, Visa, Mastercard. Visa and Mastercard are newest entrants to stock market but have quickly grown to be in top 20 US companies with market cap of about $500B each as of 2023.

US companies:

These are the largest 50 companies in USA in terms of their market cap. They are adjusted daily, and you also look at historical data since Feb 2009.

http://www.iweblists.com/us/commerce/MarketCapitalization.html

What the above link shows us is that your company is not even in largest 50 companies in USA unless you are worth > $125B in market cap. The combined market of these 50 largest companies is about $17T, which is half of the total market cap of all US companies. So, just 1% of the companies in USA account for half of stock market capitalization. Bottom 99% of the companies are like bottom 99% of poor population. Just 10 years back in Feb, 09, there was only 1 company with > $200B in market cap, and that was Exxon Mobil. Now that company sits at #44 as of Sept, 2020, and may pretty soon be out of this 50 list (who knows?). Fortunes change fast !!

UPDATE Apr, 2024: As of Apr 2024, Exxon Mobile has a market cap of $500B and is back in Top 15. Fortunes do change fast !!

http://www.iweblists.com/us/commerce/MarketCapitalization_Feb09.html

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Published: Wednesday, 08 November 2023 17:31

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RISC - V (RISC - Five)

• RISC-V is the open source ISA available that you are free to use in your designs. No licenses, royalty, etc. Website for RISC-V is here: https://riscv.org/
• Many cores have been implemented using this ISA. You can download source code for Cores, SOC or even buy the processors which are built using this ISA. Link to download here: https://github.com/riscv/riscv-cores-list
• SiFive is one the front running company building processors based on RISC-V ISA. Lot of info on: https://sifive.com
• A video on basics of  RISC-V ISA: https://www.youtube.com/watch?v=m8DqCTogb8w

RISC-V ISA:

Official RISC-V ISA manual: https://riscv.org/wp-content/uploads/2017/05/riscv-spec-v2.2.pdf

Very good ISA intro => https://www.allaboutcircuits.com/technical-articles/introductions-to-risc-v-instruction-set-understanding-this-open-instruction-set-architecture/

RISC-V ISA is extensible so that it can be used for very basic microcontrollers, and also for complex super computers. In order to figure out what extension of ISA we are working with, we have a naming convention.

RV[###][ab..yz] => RV means RISC-V arch, [###] indicates width of reg file and size of user addr space, it may be 32, 64 or 128 bits. [ab...yz] indicates the set of extensions supported by an implementaion.

Extensions supported are as below: Number of reg and their width depends on the extension.

• I = Integer => This inst set is the only reqd extension in RISC-V, and defines 47 instructions.
• M = Integer Multiplication and Division
• G = General purpose which includes inst from I,M,A,F,D extensions
• C = an alternative compressed 16 bit encoding for a special subset of existing inst.
• A = Atomic extensions and many more std extension
• Many non-std extensions allowed too, and denoted as Xext.

ex:

• RV32I => Most basic RISC-V implementation. It's reg file is 32 bit, and supports Integer only.
• RV64GCXext => 64 bit (G=general purpose IMAFDC, C=16 bit compressed inst) + a non std extension
• RV32I/RV64I => they have 32 Int reg. F and D ext have 32 FP reg too. RV32E has only 16 integer reg for use in embedded devices.

RISC-V yields smallest code size for 32 and 64 bit processors compared to x86, ARM, MIPS, etc. RV32C or compressed version of ISA is the smallest code.

Reg File:

Reg: x0-x31. x0 is a "zero reg" hard wired to 0. NOTE: The ABI (application Binary i/f) names of the reg are different, and shown in link above.

Base Integer ISA (encoded in 32 bits) are for following:

• Addition:
• Subtraction:
• Bitwise op:
• Load/Store:
• Jump:
• Branch:

More inst:

• AMO (atomic mem op) perform read-modify write in a single atomic op.
• FENCE inst form a barrier. All inst preceeding FENCE must complete before proceeding. These are used t enforce program order.
• CSR (ctl and Status reg) inst and ECALL (environment call inst) to change privilege modes.
  • MM has ~17 CSR. (ex: Misa(m/c ISA reg), mstatus(m/c status), etc)

Modes:

Modes are privilege levels supported by RISC-V. We have 3 modes.

• Mode 3 or Machine mode (MM) is the highest privilege mode and the only required mode.
• Mode 2=Hypervisor,
• Mode 1=Supervisor,
• Mode 0=User/application.

These modes are also put as levels which correspond to diff combo of modes -  level 1 to level 4.

RISC-V also supports Virtual memory allowing for sophisticated mem mgmt and OS ctl (as Linux, etc). This requires an S-Mode implementation - Sv32, Sv39, Sv48 corresponding to 32 bit, 39 bit and 48 bit virtual mem. Physical mem protection is also supported for up to 16 regions, where we can restrict access to those regions.

RISC-V supports interrupts. CSR reg used to enable/disable specific interrupts or to see the status of any interrupt.

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Published: Wednesday, 08 November 2023 05:32

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Prepositions and Adverbs:

Prepositions are words that show the relationship between elements in a sentence. Simply put, prepositions are connector words. These connectors customarily tie a noun to an idea.  An example of this is in the sentence, “I went to the store.” “To” connects the location of “store” to where the person went. So,"to" is a preposition. A preposition takes an object. If there’s a noun following the term, it usually indicates the term is a preposition

Adverbs are similar to Prepositions, but slightly different. An adverb doesn’t take an object. Adverbs such as these usually appear at the end of the clause or sentence. 

ex: "He ran down the stairs", then down is a preposition, since the noun "stairs" appears after the term "down". If it's "He ran down", then "down" is an adverb since there's no object.

ex: Maria looked out the window. => Here out is a preposition, since object "window" is present. If it's "We’re going out at 7:00 pm tonight", then out is an adverb, as there's no object, It's just the time that's mentioned.

Spanish language has same word for different prepositions, so it's very hard to learn how to use them properly. They are the ones that are mastered the last, but are used the most. Many words are both adverbs and prepositions, and their usage with or without an object determines what they classify as. We'll go over basic prepositions and adverbs (they are not strictly one or the other but general guidance).

Prepositions:

Often a preposition is a short word such as but, for, and, etc.

• pero => but (i.e I want to go, but I can't => quiero ir, pero no puedo). Also used as "yet", which is similar to "but". ex: yet I failed => but still I failed.
• para => for
• por => By
• y (pronounced spanish "e" or English "a") => and. i.e Balls and balloons.
• o => OR. Do you like tennis or Football? => ¿te/le gusta el tenis o el fútbol? =>  gustar is explained under -ar verb separately.

Adverbs:

Often adverbs are words like If, then, with, to, etc.

• Si => If. This is w/o an accent. If we put an accent on i, then Sí (with an accent on i) => yes.
• con => with.
• a => To (we saw this in verb section and personal "a" section).
  • al => To the. If "a" is followed by el (masculine noun), we combine them to form short cut +el = al. See in "ir verb" section.
• en => in/on. It can mean either "in", "on","at", "inside", etc and meaning is clear from context. estar form is used as it's location.
  
  • in: estoy en casa => I'm in the house
  • on: el libro está en la mesa => the book is on the table. If we used "la caja", then en will mean "in" as most likely "it's in the box".
• de => of or from. Most commonly used meaning of "de" is of, but sometimes it means "from" too. There are many other meanings too depending on context.
  
  • of:
    • el presidente de Francia => the president of France
    • to the right/left of => a la derecha de / a la izquierda de
  • from:
    • Soy de Londres. I’m from London.
  • del => of the / from the. If de is followed by el (i.e masculine noun), we combine the 2 words to form "de+el=del". el is used as "the" for masculine nouns, so del only appears with masculine nouns (of + the + masculine noun). If we have feminine nouns that require la, then de + la remain separate.
    • Es la casa del padre de mi amigo => It is the house of my friend’s father (the father of my friend). Since it's "de el padre", it becomes "del padre"
      
    • Es la casa de la madre de mi amigo. Here, because madre is feminine, you use la, (don't combine de and la)
      
    • He is from the market => él es del mercado. If it was "from the class", then it's "de la clase"
• sobre => about. ex: I want a book about cars => quiero un libro sobre autos
• adentro / afuera => inside / outside
  
  • ex: ¿Dónde están las llaves? => Where are the Keys? Response would be "The keys are inside / outside" => las llaves están adentro / afuera (we can drop "las llaves" as is generally donw with I, you in spanish). So simply "están adentro / afuera"
• cada/todo/todos=> each/all (see in "numbers" section)
• tambíén => Also. as well, too
  
  • ex: él también tienes mucho talento => He too has a lot of talent.
• entonces => then or so. As we use in common sentences. ex: Then what? => ¿entonces qué?

Prepositional Pronouns (PP):

When Pronouns are used after a preposition, they are known as prepositional pronouns (PP). Ex: This is for him. Here "him" has preposition "for", so it's a PP, and has to follow the table below. The transformation table for PP remains same for all entries of 3x2 table, except for 1st and 2nd person singular. There is one other rule with "con" => 1st and 2nd table entries change to combine con with PP. It becomes con+PP+go all in 1 word. See below.

 NOTE: him, her, them, us, etc should have followed DOP/IOP tables shown in Pronouns section. But instead since they have prepositions, they follow the below table.

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Published: Tuesday, 07 November 2023 02:35

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Bones and Muscles:

Very imp part of our body are bones and muscles.

Bones:

Childhood and adolescence is the period of greatest bone density. All through your life, your body is continually removing old bone and replacing it with fresh bone. This process is called remodeling. Until 30, we tend to gain more bone mass than we lose. After 30, reverse happens. Up until about age 40, all the bone removed is replaced. After age 40, however, less bone is replaced and we start losing bone mass. Once bones start getting brittle and weak, it can lead to disease like rickets and osteoporosis. it's very difficult to make them stronger again, so try to keep bones healthy in your young age. According to the American Academy of Orthopaedic Surgeons (AAOS), 50 percent of Americans over age 50 have weak bones. 80% of them are women, as their bones are smaller and thinner. Additionally, levels of the female hormone estrogen, which helps protect bones, declines sharply after menopause. No wonder, for women, we see so many more bone issues. So for women, protecting bones is even more important.

Bone mass vs Bone density: Bone weight is about 15% of body weight, but that is not a useful metric. Bone density is more important metric for bone health. The DXA (central dual-energy X-ray absorptiometry) test measures your bone density compared to the bone density of a healthy young adult. Your score on the test is called your T-score. The normal healthy adult gets a T-Score of 0. If your T-score is more than one point (called a standard deviation) below 0, you may have weak bones, explains NIH. If your T score is between -1 and -2.5, you have low bone mass. If your score is -2.5 or lower, you have osteoporosis. Women are more prone to osteoporosis because of smaller bones.

Article from John Hopkins about bone maintenance => https://www.hopkinsmedicine.org/health/conditions-and-diseases/osteoporosis/osteoporosis-what-you-need-to-know-as-you-age

Few tips to keep bones healthy:

• Calcium + Vitamin D: Your bones store roughly 98 percent of the calcium in your body. Because calcium is important for many body functions, if you don't have enough, your body will take calcium out of your bone bank, thus weakening them. Take 1g of Calcium everyday (For people over 50, 1.2g is recommended). Foods like cheese, yougurt, milk, salmon, etc contain calcium. While calcium is the biggest bone-health player, your body also relies on Vitamin D, Vitamin K, Potassium and Magnesium to build strong bones. Vitamin D is needed to help calcium get absorbed into body. There are 2 sources of getting Vit D - one thru exposure to UV rays from sun, and other thru food. Very few foods (eggs, Orange Juice, cereals, salmon, etc) contain enough Vit D, so Vit D supplements are needed. Recommended amount is 1000 IU of Vit D every day. Upper safe limit is 4000 IU per day. 1000 IU is 25 microgram (0.025 mg or 25 mcg) of Vit D, so very small amount of Vit D is enough. Vit D helps with many other functions of our body too (helps build your immune system), so make sure you get enough. Indians have very low levels of Vit D, so make sure you take supplements with 2000-5000 IU. I've myself taken 50,000 IU Vit D supplements (once a week, prescribed by Doctor), as Vit D levels have been too low. That barely got me into the acceptable range. Recommended range for Vit D is b/w 30-100 in your blood test.
  
  • For vegetarians, 1 glass of milk (250ml) has 25% calcium and 25% Vit D requirement of an adult. Here milk is fortified with Vit D (sold in USA). Even Orange Juice come with fortified Calcium and Vit D, so take those.
  • Vit D: Vit D exists in 2 forms - Vit D2 and Vit D3. Vitamin D2, or ergocalciferol, is found in fungi (mushrooms) and yeasts. Vitamin D3, or cholecalciferol (koli-kal-ciferol) is produced by the body via sunlight (Thru sunlight, the skin converts 7-Dehydrocholesterol into Vit D3) or ingested via food. Liver converts this cholecalciferol into 25-Hydroxycholecalciferol, which the kidneys then convert into 1, 25-DiHydroxycholecalciferol. This is also called calcitriol, which is the active form of Vit D. This moves into the small intestine, which then increases the number of calcium binding proteins. That helps with calcium absorption. Vit D3 is more important. When we say Vit D, we always mean Vit D3. Video on Vit D: https://www.youtube.com/watch?v=iLDYbSX5MLA
• Exercise: Higher bone density is needed for stronger bones, and exercise helps with that. Lifting weights, running, biking all make your bones stronger.

Cartilage: This is a covering over the bone, seen in the thigh bone, where it meets the shin bone.

Muscles:

Few terms for diff kinds of muscles:

• Ligaments => Soft tissue structures that connect bone to bone.
• Tendons => These are much like Ligaments except that they connect bones to muscles. Muscles move the bones by pulling on the Tendons

Knee Basics:

Knees are the most important part of the bone structure and the most fragile. They are the first ones to give up due to old age, or plain wear and tear. It's important to consider knees in it's own section.

Knee bone basics: https://www.youtube.com/watch?v=_q-Jxj5sT0g

Meniscus tear: This is one the common tears that you can get very easily. Once you get it, it's very difficult to fix by itself. Doctors will want to do surgery, but don't fall for it.

Good advice on this link: https://kingbrand.com/Meniscus-Information.php?msclkid=fb0a365fb9521e7e41d353ed1bb57eaa

 Parts of Knee:

• Meniscus: These are C shaped shock absorbers between the thigh bone and shin bone, and help with the impact when the 2 bones aremoving aginst each other. It's made of cartilage, and hence has a poor blood supply. A tear in meniscus can cause lockup, giving out, pain when squatting, lifting weight, etc. Lock up or giving out is when you cannot straigten your knee completely while running. The torn parts of meniscus get in between the 2 bones, and cause pain. A Surgery is done to shave off these lose parts, and get them out of your body, which relives the pain. But then you have less of miniscus left, which may increase your chances of getting  arthritis down the line.