JSON-RPC is a remote procedure call protocol encoded in JSON. It allows communication between a client and a server, where the client sends requests to the server, and the server responds. In the context of blockchain and cryptocurrencies, JSON-RPC is often used to interact with nodes. Users or applications can send commands to a node to perform various operations, such as retrieving blockchain data, sending transactions, or querying account balances. Each request consists of a method name, parameters, and an ID that allows tracking of the response. The server processes the request and returns a JSON-formatted response with the result or an error message. This protocol is lightweight and easy to use, making it suitable for applications that need to communicate frequently with blockchain networks. Many cryptocurrencies have APIs that implement JSON-RPC, allowing developers to build applications that can efficiently interact with the blockchain.