Full Node

A full node is a program that fully validates transactions and blocks in a blockchain. It’s essentially a computer connected to a cryptocurrency network that keeps a complete copy of the entire blockchain. This involves all of the transactions that have ever occurred on that particular network.

Full nodes enforce the rules of a blockchain to all transactions and blocks. When a transaction or block doesn’t meet the rules, it is rejected by the full node, which helps keep the network secure and decentralized.

They serve several functions:

1. Block validation: Full nodes validate each block on the chain to ensure it complies with the rules of the blockchain. This is important because it prevents fraud and double spending.
2. Transaction validation: In addition to validating blocks, full nodes also validate individual transactions. This ensures that only legitimate transactions (i.e., those not attempting to double-spend or otherwise break the rules of the blockchain) are added to the blockchain.
3. Serving the blockchain to other nodes: Because a full node has a complete copy of the blockchain, it can serve historical blocks to other nodes, helping them to sync with the network.
4. Security: Full nodes contribute to the security of the network. The more full nodes there are, the more difficult it is for a single entity to take control of the network.

Running a full node is not necessary for most users of cryptocurrencies, but it does contribute to the health and robustness of the network. It also gives you a higher level of privacy and security because you validate transactions locally without needing to trust a third party.