Component
Program parts that contain any of a variety of functions. Also, the term component not only pertains to programs, but also to any hardware or system parts.
Software components contain a variety of special functions, but as a rule these functions cannot be used except in tandem with other programs, and components are linked with programs for the purpose of executing these functions. Therefore, it can be said of components that as objects in themselves they may have special functions, but are without meaning unless combined with a something else.
As Java and other object-oriented languages continue growing in prominence, there has been a concomitant increase in software that links components, and the distinction between component developers and software developers has sharpened alongside this trend. This development of software designed to combine components is known as "Component Base Programming".