callees

Callees are the recipients of a call in various contexts. In programming, the callee is the function or method that is invoked by a caller. During a call, control is transferred from the caller to the callee, which processes input parameters, executes its body, and returns control and a value to the caller. The callee typically creates a local stack frame, saves and restores registers as required by the platform's calling convention, and may allocate resources. Calling conventions define how arguments are passed, how the return value is delivered, and who cleans up the stack.

In telecommunications, the callee is the recipient of a telephone call—the person or device addressed by the caller. The callee may answer, ignore, or route the call to an endpoint such as voicemail, an automated attendant, or a conference bridge. Callees can be human users, machines, or network endpoints.

In distributed systems and APIs, the term is used to describe the endpoint that handles a request from a caller, such as a service in a microservices architecture or a function exposed by an API. The callee processes the incoming request, performs the necessary work, and returns a response to the caller, typically over a network protocol with a defined contract.

The relationship is defined by the context, but the underlying idea is that a caller transfers control to the callee in the course of a call.