Service

Service is an application that provides information and/or functionality to other applications. Services are typically non-human-interactive applications that run on servers and interact with applications via an interface. A service may expose a synchronous, programmatic interface (i.e., an API), allowing it to be tightly-coupled with a consumer, or use asynchronous, message-based communications (e.g., HTTP, XML, and SOAP) to remain very loosely-coupled with consumers. Services are an essential part of distributed architecture program design.