Mining is the process of spending computation power to secure Bitcoin transactions against reversal and introducing new Bitcoins to the system. Technically speaking, mining is the calculation of a hash of the block header, which includes among other things a reference to the previous block, a hash of a set of transactions and a nonce (an arbitrary number used just once for authentication purposes).
Armory’s fragmented backups is another useful feature. Instead of requiring multiple signatures for each transaction, fragmented backups require multiple signatures only for backups. A fragmented backup splits up your Armory backup into multiple pieces, which decreases the risk of physical theft of your wallet. Without a fragmented backup, discovery of your backup would allow for immediate theft. With fragmented backup, multiple backup locations would need to be compromised in order to obtain the full backup.
Hot wallets refer to Bitcoin wallets used on internet connected devices like phones, computers, or tablets. Because hot wallets run on internet connected devices there is always a risk of theft. Think of hot wallets like your wallet today. You shouldn’t store any significant amount of bitcoins in a hot wallet, just as you would not walk around with your savings account as cash.
Correction (Dec. 18, 2013): An earlier version of this article incorrectly stated that the long pink string of numbers and letters in the interactive at the top is the target output hash your computer is trying to find by running the mining script. In fact, it is one of the inputs that your computer feeds into the hash function, not the output it is looking for.

A few miles from the shuttered carwash, David Carlson stands at the edge of a sprawling construction site and watches workers set the roof on a Giga Pod, a self-contained crypto mine that Carlson designed to be assembled in a matter of weeks. When finished, the prefabricated wood-frame structure, roughly 12 by 48 feet, will be equipped with hundreds of high-speed servers that collectively draw a little over a megawatt of power and, in theory, will be capable of producing around 80 bitcoins a month. Carlson himself won’t be the miner; his company, Giga-Watt, will run the pod as a hosting site for other miners. By summer, Giga-Watt expects to have 24 pods here churning out bitcoins and other cryptocurrencies, most of which use the same computing-intensive, cryptographically secured protocol called the blockchain. “We’re right where the rubber hits the road with blockchain,” Carlson shouts as we step inside the project’s first completed pod and stand between the tall rack of toaster-size servers and a bank of roaring cooling fans. The main use of blockchain technology now is to keep a growing electronic ledger of every single bitcoin transaction ever made. But many miners see it as the record-keeping mechanism of the future. “We’re where the blockchain goes from that virtual concept to something that’s real in the world,” says Carlson, “something that somebody had to build and is actually running.”
Bitcoin miners were now caught in the same vicious cycle that real miners confront—except on a much more accelerated timeframe. To maintain their output, miners had to buy more servers, or upgrade to the more powerful servers, but the new calculating power simply boosted the solution difficulty even more quickly. In effect, your mine was becoming outdated as soon as you launched it, and the only hope of moving forward profitably was to adopt a kind of perpetual scale-up: Your existing mine had to be large enough to pay for your next, larger mine. Many miners responded by gathering into vast collectives, pooling their calculating resources and sharing the bitcoin rewards. Others shifted away from mining to hosting facilities for other miners. But whether you were mining or hosting, mining entered “a scaling race,” says Carlson, whose own operations marched steadily from 250 kilowatts to 1.5 megawatts to 5 megawatts. And it was a race: Any delay in getting your machines installed and mining simply meant you’d be coming on line when the coins were even harder to mine.
The receiver of the first bitcoin transaction was cypherpunk Hal Finney, who created the first reusable proof-of-work system (RPOW) in 2004.[21] Finney downloaded the bitcoin software on its release date, and on 12 January 2009 received ten bitcoins from Nakamoto.[22][23] Other early cypherpunk supporters were creators of bitcoin predecessors: Wei Dai, creator of b-money, and Nick Szabo, creator of bit gold.[24] In 2010, the first known commercial transaction using bitcoin occurred when programmer Laszlo Hanyecz bought two Papa John's pizzas for 10,000 bitcoin.[25]