Blockchain is powered by a large network of miners. Those miners can be either single computing devices… or entire farms of computing devices networked together.

A node is simply any computer that is part of a blockchain’s network.

There are 2 kinds of nodes:

  • A full node is a node which itself holds a full copy of the blockchain. Full nodes are necessary in a decentralized blockchain to ensure the security and integrity of the blockchain. The data could not be altered by anybody because there are all the other copies on other full nodes to compare to.
  • Lightweight node is a node which helps power the network, but doesn’t necessarily hold a full copy of the blockchain. This kind of node would need to stay in sync with a full node in order to participate in the network.

The term consensus is often used in blockchain. Consensus refers to the act of the full nodes on the network staying in sync and verifying the blockchain blocks with each other.