Читать книгу Bitcoin For Dummies - Peter Kent - Страница 39

The Bitcoin ledger — the record of Bitcoin transactions — is saved in the Bitcoin blockchain. What’s a blockchain, you ask? A blockchain is a very special type of database. So once again, we need to step back — very quickly this time — to ask, what’s a database?

Quite simply, a database is an electronic store of information, that is being stored in a structured format on a computer. If you open a word-processing file and type a bunch of names and addresses into a document and save it, that’s not really a database; it’s just a jumble of information. But if you open a spreadsheet document and save the names and addresses — first name in the first column, last name in the second column, street address in the third, and so on — then you are creating a form of simple database where the information is stored in an organized, structured format.

Blockchains are a form of database; more specifically, they are specialized, sophisticated databases with special features that make them immutable unchangeable and unhackable.

The first significant characteristic is (and perhaps once we’ve said this, it may not be a surprise) that the blockchain uses blocks of data that are, um, chained together in a manner that makes it impossible to change any piece of data — a particular transaction, for instance — without changing the entire chain of blocks (we’ll explain how that works in a moment).

The other important characteristic is that the blockchain database is duplicated and distributed. Let’s look at these two issues one by one, starting with the duplication and distribution.