Blockchain Academy
We'll get together for networking with people interested in Blockchain including developers and anyone curious about Blockchain.

Node

Node in communications network refers to all of communication device such as computers linked with the local network. Node in blockchain is a minimum unit of member constructing the network. As shown in the image below, each circle is a node building the network, and all nodes share and verify data with a P2P method in a decentralized network. There are many definitions for a node, but it is easy to think it as just a member of participants in a blockchain.

There are various roles of nodes according to the blockchain consensus algorithm. Nodes in some blockchains are able to create and verify the blocks on the minute they participate in the network, but in some other blockchains only specific nodes can do this work.

Nodes can be classified by their roles in a blockchain.

Full Node

This is the node which contains all the transactions from the first block, 'genesis block' up till now. Holding a tremendous block size of full data, its memory exceeds over 200 gigabytes. It verifies the transactions by itself without other node's help, because it contains all the data of the blocks. It is mandatory to have the data of a full node for mining.

Light Node

Unlike a full node, a light node is a small node contains only block header's information. It only verifies an individual transaction, so for the actual transaction verification, it needs to request the data from a full node.