Yesterday I received an unexpected gift: a link to a copy of the slides of the presentation that 21inc gave to investors, apparently between October and December 2014, when they were still calling themselves "21E6".
(The sender asked to remain anonymous, and I am not sure about the copyright status of the file; so I would rather not repost it here yet. But it seems that several other people, including some of the 21inc competitors, have got a copy too; so anyone who is really interested can probably get it too.)
The slides don't have much new factual information, and basically confirm what we already guessed about the 21inc business plans. But they show that we severely underestimated their chutzpah and hype. Here are some random highlights (as far as I can decipher from the slides):

• Mining operations:

They had three relevant mining rig designs in the plans, that would require funding:

Codename Qty TH/s kW Cost Deploy Turnoff Profit($) --------------- ---- ---- --- ---- ------------ ----------- ----------- CyrusOne(v2), 7904 2.0 1.3 --- (already on) Apr 2015 ~23,000,000 IO(v1v3) 3250 5.2 1.3 2000 Jan 2015 Aug 2016 ~24,000,000 Brownfield(v3) 1900 5.5 1.3 2450 Mar 2015 > Nov 2017 ~20,000,000 

The "TH/s", "Cost", and "kW" columns are per "system", i.e. a mining unit containing many chips. The last column is the expected profit to be made from each set of mining hardware over its expected lifetime. (The slides have some other details that do not seem to be important.)
The first line is the hardware that they were mining with at the time of the presentation; that must be why the "Cost" (as far as investors are concerned) is given as zero.
The second line seems to be an upgrade of their previous mining hardware from v1 chips (which gave 2.7 PH/s total at the time) to v3 chips (which would give 17 PH/s) .
In reality, we have seen that their share of hashpower dwindled through all of 2015, and (AFAIK) they haven't mined a single block in the last six months. Were they still mining with CyrusOne on extra-life, or were they using the upgraded IO which was turned off prematurely? What happened to Brownfield?

• BitSplit chip:

However, their mining operations were secondary; the meat of their plan was the embedded chip, called BitSplit at the time.
The BitSPlit chip (as we suspected) was hard-wired to send 75% of the block reward to the 21inc wallet, whose address was burned in the silicon, and 25% to the user's wallet.
By my calculations, assuming 50 GH/s and no increase in the difficulty, the BitSplit would mine one block in 570 years, on average, and collect less than 2 BTC of reward in that time. So, of course, the chip was hard-wired to mine into a pool run by 21inc, that would spread the user's 25% of those 2 BTC (expected) into a daily regular trickle of a couple thousand satoshis. Their own mining operations would provide the BTC needed for the pool payouts of all the millions of chips that they expected to be running out there.
They projected to release 3 versions:

Model Qty GH/s W Cost Deploy Profit($) --------------- ---------- ---- -- ---- ------------ ------------ USB hub-charger 250,000 38 15 $35 Mar 2015 ~8,000,000 Embedded chip 1,000,000 63 15 $8 Aug 2015 ~103,000,000 BitSplit Inside 10,000,000 20 5 $0 Oct 2015 ~292,000,000 

The "Qty" is the expected number of units sold. The last column, IIUC, is the profit that 21inc expected to make from the 75% cut of the BTC produced by all the chips, over their expected lifetime.
In the above "USB hub-charger" model was a USB charging unit, roughly 3 x 2 x 1 inches, with 2 USB outputs and a mining chip inside, produced by 21inc themselves "to seed the market".
The second line, which I called "Embedded chip", seems to refer to discrete BitSplit chips provided by 21inc and included in consumer devices (like routers etc.) by OEM manufacturers.
The "BitSplit Inside" model would be the BitSplit integrated into the chipsets of other manufacturers, and manufactured by them. Its cost is listed as "$0" (for 21inc) because they expected those manufacturers to shoulder the cost of manufacturing and integrating the mining chip.
Apparently the market-seeding "USB hub-charger" was later replaced by the "Bitcoin Computer" (aka the PiTato). In one slide it is called "multifunctional BitSplit device", and depicted as a sleek shiny black box, the size of a cigarette pack, with a power cable and 2-3 USB or similar outputs. If that is supposed to be the PiTato, presumably they had not yet realized that a 15 w computer would need a cooling fan with a miniature wind tunnel on top.
In the last two entries, the manufacturers (not the device owners!) would be rewarded with the 25% slice of the BTC mined by those embedded chips. As an example, the slides say that a manufacturer who produced one quarter of the embedded BitSplits would get the 25% cut on the BTC yield of those chips, that was estimated to be between 2 and 4 million dollars per year of revenue in 2015--2018. Those numbers are based on the following predicted mean BTC prices: $350 for 2015, $1000 for 2016, $2200 for 2017, and $5500 for 2018.

So, their main business plan was fantastic: the OEM and chipset makers would pay the costs of producing and integrating the chips, the consumers would pay the cost of operating them, and 21inc would get 75% of all BTC mined by them, expected to be worth 400 million dollars.
It makes sense to invest 100 million in that plan, right?
EDIT1: Sentence order, typos.
EDIT2: See also this comment below about other sources of this info and this comment about a fatal flaw of the PiTato mining chip.
EDIT3: See also this comment with the data from slide 2, "At a glance"

Welcome to the /Bitcoin Sticky FAQ

Maybe you're here because you've received a tip on social media, or maybe you've just been hearing a lot recently about Bitcoin and are wondering what the big deal is? The following videos are a good starting point for understanding how bitcoin works and a little bit about its long term potential:

• Video 1: What Is Bitcoin & Why Should You Care?
• Video 2: The real value of bitcoin and crypto currency technology
• Video 3: Bitcoin Is Independent Money
• Video 4: Bitcoin 101 - Bilaji Srinivasan

For lots of additional video resources check out the videos wiki page or /BitcoinTV . Peer-reviewed, research papers can be found here.

Where can I buy bitcoins?

You can buy or sell any amount of bitcoin (from as little as $1 worth) and there are several easy methods to purchase bitcoin with cash, credit card or bank account. A good list of exchanges sorted by region can be found on the exchanges wiki here.
Note: Bitcoins are valued at whatever market price people are willing to pay for them in balancing act of supply vs demand. Unlike traditional markets, bitcoin markets operate 24 hours per day, 365 days per year. Here are a couple useful sites [bitkoin.io, preev.com] that shows how much various denominations of bitcoin are worth in different currencies. Alternatively you can just Google "1 bitcoin in (your local currency)".

Where can I spend bitcoins?

Store	Product
Microsoft	Xbox games, phone apps and software
Spendabit and The Bitcoin Shop	Search engines of online retailers accepting bitcoin with millions of results
Overstock and Rakuten	Everything under the sun
Gyft	Gift cards for hundreds of retailers including Amazon, Target, Walmart, Starbucks, Whole Foods, CVS, Lowes, Home Depot, iTunes, Best Buy, Sears, Kohls, eBay, GameStop, etc.
NewEgg, TigerDirect and Dell	For all your electronic needs
Expedia, Cheapair, Destinia and 9flats	For when you need to get away
BoltVM, Namecheap, Mullvad and PIA	Handy web services
Foodler and Takeaway	Takeout delivered to your door!
HumbleBundle, GreenmanGaming, and Coinplay.io	For when you need to get your game on
Reddit Gold	Premium membership which can be gifted to others

Coinmap and AirBitz are helpful to find local businesses accepting bitcoins. UK residents can find a comprehensive directory of shops, pubs, websites and other places in the UK that accept bitcoins at wheretospendbitcoins.co.uk.
There are also lots of charities which accept bitcoin donations, such as Wikipedia, Red Cross, Amnesty International, United Way, ACLU and the EFF. You can find a longer list here.
Additional resources can also be found at TheBitcoinPage.com

Merchant Resources

There are several benefits to accepting bitcoin as a payment option if you are a merchant;

• 1-3% savings over credit cards or PayPal.
• No chargebacks (final settlement in 10 minutes as opposed to 3+ months with credit cards / PayPal).
• Accept business from a global customer base.
• Increased privacy for your customers.
• The payment processor can convert 100% of the sale to the currency of your choice for deposit to your account which means there is no need to hold bitcoins and no exposure to price volatility. Alternatively, you can choose to keep a certain percentage of the sale in bitcoin if you wish to begin accumulating it.

If you are interested in accepting bitcoin as a payment method, there are several options available;

• BitPay
• Coinbase
• Coinify
• Coinkite
• Snapcard
• GoCoin
• BitMerchant

Can I mine bitcoin?

Mining bitcoins can be a fun learning experience, but be aware that you will most likely operate at a loss. Newcomers are often advised to stay away from mining unless they are only interested in it as a hobby similar to folding at home. If you want to learn more about mining you can read more here. Still have mining questions? The friendly folks at /BitcoinMining would be happy to help you out.
If you want to contribute to the bitcoin network by hosting the blockchain and propagating transactions you can run a full node using this setup guide. You can view the global node distribution here.

Securing your bitcoins

With bitcoin you can "be your own bank" and personally secure your bitcoins OR you can use established companies such as Coinbase and Circle which have secured wallets where they hold the bitcoins for you and provide insurance.
If you prefer to "be your own bank" and have direct control over your coins without having to use a trusted third party, there are many options in the wallets wiki. If you would prefer easy and secure storage without having to learn computer security best practices then a hardware wallet such as the Trezor, Ledger or HW-1 is recommended.
Note: For increased security, use Two Factor Authentication (2FA) everywhere it is offered, including email!
2FA requires a second confirmation code to access your account, usually from a text message or app, making it much harder for thieves to gain access.

Google Authenticator	Authy
Android	Android
iOS	iOS

Earning bitcoins

Just like any other form of money, you can earn bitcoins by working for them. Here are a few resources for bitcoin jobs.

• /Jobs4Bitcoins
• Coinality job board
• Bitgigs job board
• Find Bitcoin Jobs

Tipping

• Use ChangeTip.com (/changetip) for tipping people on Facebook, Reddit, Twitter, YouTube, Tumblr, Google+, GitHub, Slack and more! (you can even use custom monikers to tailor your tip to the discussion or add a bit of humor). Read more about ChangeTip at their reddit wiki.
• Go to /FreeBits to get a few bits to practice with and then tip them forward. Go to /BitTippers to play games and solve riddles to earn your bits. Don't forget your flair!

Fundraising

You can use Lighthouse to crowdsource fundraising initiatives with bitcoin. It's similar to Kickstarter, but without intermediaries or exorbitant fees. You can participate in project discussions at /LighthouseProjects, and watch the progress of fundraisers at lightlist.io.

Bitcoin Projects

The following is a short list of ongoing projects that might be worth taking a look at if you are interested in current development in the bitcoin space.

Project	Description
Lightning Network	Payment channels for network scaling
Blockstream	Sidechains
Open Transactions, Counterparty, Omni, Open Assets, Symbiont and Chain	Financial asset platforms
Augur and Mirror	Prediction markets
Factom	Records & Titles on the blockchain
Open Bazaar, Provistor and Bitmarket	Decentralized free markets
Zerocash, Dark Wallet and Joinmarket	Privacy enhancement
ShapeShift.io	The easiest way to swap between bitcoin and altcoins
BitShares	Decentralized exchange
Keybase and Bitrated	Identity & Reputation management
Bitmesh and Telehash	Mesh networking
JoyStream	BitTorrent client with paid seeding
Maidsafe	Decentralized internet
Storj and Sia	Decentralized file storage
21e6	Internet of things??
Streamium	Decentralized video streaming
Abra	Global P2P money transmitter network
bitSIM	PIN secure hardware token between SIM & Phone
Identifi	Decentralized address book w/ ratings system
Coinometrics	Institutional-level Bitcoin Data & Research
Blocktrail	Multisig bitcoin API
Copay	Open source mulltisig wallet by BitPay
Bitcore	Open source javascript library by BitPay
Insight	Open source blockchain API by BitPay
Foxtrot	Open source routing network from BitPay
La'Zooz	Decentralized Ridesharing
Leet	Kill your friends and take their money ;)
Lawnmower	Spare change into bitcoin

Bitcoin Units

One Bitcoin is quite large (hundreds of £/$/€) so people often deal in smaller units. The most common subunits are listed below:

Unit	Symbol	Value	Info
millibitcoin	mBTC	1,000 per bitcoin	SI unit for milli i.e. millilitre (mL) or millimetre (mm)
microbitcoin	μBTC	1,000,000 per bitcoin	SI unit for micro i.e microlitre (μL) or micrometre (μm)
bit	bit	1,000,000 per bitcoin	Colloquial "slang" term for microbitcoin
satoshi	sat	100,000,000 per bitcoin	Smallest unit in bitcoin, named after the inventor

For example, assuming an arbitrary exchange rate of $500 for one Bitcoin, a $10 meal would equal:

• 0.02 BTC
• 20 mBTC
• 20,000 bits

If you want to use 'bits' exclusively, just remember that there are 100 satoshis in 1 bit, and 1 million bits in one bitcoin. For more information check out the Bitcoin units wiki.
Still have questions? The friendly folks at /BitcoinBeginners would be happy to help you out, or stick around for our weekly Mentor Monday thread. If you decide to post a question in /Bitcoin, please use the search bar to see if it has been answered before, and remember to follow the community rules outlined on the sidebar to receive a better response. The mods are busy helping manage our community so please do not message them unless you notice problems with the functionality of the subreddit. A complete list of bitcoin related subreddits can be found here
Note: This is a community created FAQ. If you notice anything missing from the FAQ or that requires clarification you can edit it here and it will be included in the next revision pending mod approval.
Welcome to the Bitcoin community and the new decentralized economy!