Account and wallet

First of all, we must clarify the difference between account and wallet.

Account
Belonging to a person, including the money at his disposal and maintaining all previous transaction records of the person.

Wallet
Belonging to a person, only includes the money that person can control.

In the Bitcoin world, there is no concept of personal accounts, only Bitcoin wallets, the so-called Bitcoin wallets, can actually be simply understood as a public key. Since everything in an electronic computer can be copied at zero cost, it is necessary to use asymmetric cryptography to solve this problem.

To put it simply, the meaning of a wallet is "anyone can put money in, but only you can take it out." The reason why you have more power to take out money than others is because you hold and share the wallet. The private key corresponding to the key! Please remember that the private key is the key for you to open the wallet and spend money. Once it is stolen by someone else, the money is someone else’s. Once lost or destroyed, the money in the wallet is equivalent to being destroyed, just like in reality. The paper money was torn up and burned.

Since there is no concept of an account, how do I know how many bitcoins I have left to spend?

In the Bitcoin world, all the money that can be spent is uniformly expressed as UTXO (that is, Unspent Transaction Output). The UTXO is associated with a wallet address. If you want to know how much money you can spend, you can only traverse what you have. Wallet, and then add the UTXO associated with the wallet together, and the result is your "account balance. All of this information is distributed and stored in the blockchain that has reached a consensus on the entire network. This will be discussed later. .

Here I usually ask, where did my UTXO come from? Very simple, it comes from two sources:

Others transfer to oneself

Self-mining income

In addition to these two ways, there will be no other ways to get you UTXO.

UTXO is the basic unit of consumption in the Bitcoin world. Just like our daily renminbi denomination, you cannot split a piece of 10 yuan into two halves. If you buy a 5 yuan thing, you have to pay the entire 10 yuan. Money, and then accept the change of 5 yuan, of course, you can also say "no need to find it!"