Читать книгу Bitcoin For Dummies - Peter Kent - Страница 15

So what is Bitcoin? Well, we can tell you what it isn’t very quickly. It’s not tangible — there’s nothing you can touch or hold. You can’t taste it or smell it. You can’t even see it. In fact — and we explain this in more detail in Chapter 2 — Bitcoin really isn’t. That is…there is no Bitcoin.

What there is, though, is something known as the Bitcoin ledger (another word, by the way, that Satoshi Nakamoto didn’t use in his famous Bitcoin whitepaper, but that is what the data stored in the Bitcoin blockchain has come to be popularly known as). A ledger is a written record of transactions; your checkbook’s little account register is a form of ledger, for instance. (For those of you under 30, a check is a piece of paper you can write a number on, sign your name, and give to someone, and that someone can then give it to their bank and the bank gives them money…an amazingly efficient system.) Or consider a bank statement, showing money coming into and leaving your account. (All too often leaving.) That’s a form of ledger, too.

So, when Satoshi Nakamoto created the first ever Bitcoin, how did he create it? Well, when we talk about Bitcoin being “created,” we’re really talking in shorthand. No Bitcoin thing was created. When Nakamoto first “created” Bitcoin, what he really did was to create a set of rules for a ledger in which he recorded the creation of Bitcoin. The ledger says, in effect, “50 new Bitcoin were created today.” And there you go, Bitcoin exists.

When Nakamoto minted that first “genesis block,” the nature of the network was set in computational stone. Buried in the first block of data was a little additional text, words from the front page of that day’s New York Times (January 3, 2009): “Chancellor on Brink of Second Bailout for Banks.” Perhaps this was a hint at Nakamoto’s reason for creating the network, as an alternative to what he felt were the corrupt government-managed monetary systems.

The ledger essentially records two things. The first is the creation of Bitcoin, which is done through a process called “mining.” Nakamoto “mined” those original 50 Bitcoins (however, the first 50 Bitcoins are unspendable due to the nature of the code). Mining continues, and in fact, new Bitcoins are created each time a new block of transactions is added to the Bitcoin blockchain, every ten minutes or so. (Chapter 7 explains how this “mining” process works.)

However, there is a mathematical arrangement to all this: Bitcoins are created on a steady schedule, and every four years or so (during an event quaintly called the halvening), the number of Bitcoins created every ten minutes is halved. Right now, 6.25 Bitcoins are created every ten minutes, but sometime in 2024, that will be reduced to 3.125, then again halved four years later, and so on (every four years) until around the year 2140, when the maximum number of Bitcoins will finally be in circulation.

The second thing that the ledger records is what happens to the Bitcoin once it has been created. As we discuss in Chapter 2, all Bitcoin is associated with “addresses” in the blockchain, and as people buy and sell Bitcoin, or use Bitcoin to buy something (essentially the same as selling Bitcoin), the coins get sent from one address in the blockchain to another. The Bitcoin ledger keeps track of where the Bitcoin flows, from address to address to address. Each address is under the control of someone, and thus the blockchain is, in effect, keeping track of who owns what. If the Bitcoin blockchain ledger says the address you control has 2 Bitcoins associated with it, then you control those 2 Bitcoins. (In Chapters 3 and 4, we explain how to exercise this control — that is, how you can transfer your Bitcoin to other addresses in return for governmental fiat currency or for goods and services.)