Bitcoin: What are nodes actually do?

What are nodes and how do they work?

The best way to get an idea of ​​what nodes are is to look at them in a typical representation of a decentralized network. Of course, you cannot look at blockchain networks, they are purely digital. Therefore we have to resort to graphical representations. It can look something like this.

We see: circles connected by lines. Transferred to the Bitcoin blockchain, each of these circles would be a node, i.e. network node.

Central properties of a blockchain are immutability, decentralization and transparency. All participants can check at any time which transaction went where and when. All information is stored in the form of transaction history in the individual nodes. So they are the decentralized cornerstones of the blockchain information network. This also means: The more nodes a network has, the more decentralized it is.

What is the function of bitcoin nodes?

When it comes to nodes, we differentiate between full, mining and lightweight nodes, each of which has different functionalities. Full nodes keep the Bitcoin blockchain running and secure by storing all transaction history.

Mining nodes are special forms of full nodes that ensure that network rules are observed. They also calculate proof-of-work functions and pin new blocks to the blockchain.

Lightweight nodes, or simplified payment verification clients, or SPV clients for short, do not store the complete history of the blockchain. They only use the block header of the previous block to verify and propagate new transactions. Typical SPV clients are bitcoin wallets.