Cryptocurrency client software can either run a full node or a lightweight client / wallet. A full node will download and maintain a complete copy of the blockchain, whereas a lightweight wallet will not need to do this.
Because every single transaction which has ever been made is recorded in the blockchain, older and more popular cryptocurrencies can have very large blockchain files. This means that they can take a long time to download when installing the client and can take up quite a lot resources on the computer hosting them.
This is not ideal for the casual user, so many people do not want to run a ‘full node’.
Having a larger number of full nodes strengthens the networks and makes it more decentralized. The number of full nodes is therefore one measure of the health of a cryptocurrency network, and users are often encouraged to run a full node if they can as a contribution to the health of the network.« Back to Glossary Index