In blockchain terminology, a client refers to a software application or program that interacts with a blockchain network. It can be a node running the full blockchain protocol or a lightweight client that communicates with full nodes. The client's primary function is to send and receive transactions, access and update the blockchain's data, and participate in the consensus process. Blockchain clients may include functionalities such as wallet management, transaction signing, and verification. They enable users to interact with the blockchain network, view account balances, send and receive digital assets, and interact with decentralized applications (dApps) built on top of the blockchain platform.