Component

Modular, deployable, and replaceable part of a system that encapsulates implementation and exposes a set of interfaces.

In programming and engineering disciplines, a component is an identifiable part of a larger program or construction. Usually, a component provides a particular function or group of related functions. In programming design, a system is divided into components that in turn are made up of modules. Component test means testing all related modules that form a component as a group to make sure they work together. In object-oriented programming and distributed object technology, a component is a reusable program building block that can be combined with other components in the same or other computers in a distributed network to form an application.