Читать книгу Bitcoin For Dummies - Peter Kent - Страница 37

Spend some time around Bitcoin folk, and you’ll start to hear talk of the Bitcoin ledger. So let’s back up a moment. What is a ledger? The Merriam-Webster online dictionary defines a ledger as “a book containing accounts to which debits and credits are posted from books of original entry.” Wikipedia defines a ledger as “a book or collection of accounts in which account transactions are recorded.”

So a ledger is a record of transactions. You’ve seen ledgers. Your bank statement, on paper or on your computer screen, is a form of ledger. Your checkbook register is a form of ledger (does anyone still use a checkbook register?). If you use Quicken or Mint or some other form of accounting program, you’ve seen ledgers.

Well, there’s also a Bitcoin ledger, and inside that ledger is a record of Bitcoin transactions. There is no actual Bitcoin, but there is a record of Bitcoin coming into your account and leaving the account. Which is pretty much what you see when you look at your bank statement, which is a record of currency transactions, too, payments to and from your account. It’s generally not, however, a record of actual, physical money transactions. In fact, in the U.S., only one-quarter of transactions are cash (mostly under $25), and more than one-half of transactions are plastic (credit and debit cards). The rest are various electronic payment methods (and a few checks).

Here’s a quick question for you: What’s the difference between U.S. dollars and Bitcoin? With U.S. dollars, 90 percent of all the money is nothing more than entries in a computer server. With Bitcoin, it’s 100 percent!

Now, the Bitcoin ledger is often described as being immutable. The word immutable means “not capable of or susceptible to change,” and of course the Bitcoin ledger can change; hundreds of thousands of transactions are added to the ledger every day. But what immutable means in this context is that once a transaction has been committed to the ledger, that’s it; it can’t be changed. The ledger can’t be “hacked” and modified, for instance. (You’ll find out why in a few moments.)

So, because the ledger is immutable, it means that whatever is recorded in the ledger is the truth. If the ledger says that you own, say, half a Bitcoin, then the fact is you own half a Bitcoin!