There are many types of blockchains. They can be mainly divided into public and private types. Public blockchains are open, and anyone can take part in their operation. They do not have specific administrators. Blockchains which are not public are called private blockchain which are operated by specific administrators or a consortium.
In addition to dividing them up this way, they can also be categorized by their level of fault tolerance, how consensus mechanism is formed, whether or not they are used for cryptocurrencies, and the like, so there are many different types of blockchains with many differing characteristics.
Below is an overview of structures and processes commonly used in many blockchains.
A blockchain system consists of multiple computers ("peers") connected via a network. Users issue processing requests via the network, and the blockchain executes and records those processes. A single unit of requested processing is called a "transaction," which contains a relatively small amount of arbitrary information.
Let's look at the blockchain transaction process using the example of Mr. A sending Mr. B 1,000 coins of cryptocurrency.
First, Mr. A creates a transaction: "Send 1,000 coins to Mr. B." He then digitally signs it. When Mr. A sends the transaction to the blockchain, a peer within the blockchain receives it and transfers it to its connected peers.
This causes transactions to be delivered to all peers (Fig. 1-①: Sending and transferring).
Each peer verifies the digital signature of the transaction it receives and moves 1,000 of Mr. A's coins to Mr. B (Fig. 1-②: Processing).