Component
A component is a discrete, structural element of a software architecture, a self-contained unit with a defined responsibility and interface that can be reasoned about, and often built or deployed, independently of the rest of the system.
"Component" is one of several names given to the same general idea, usually called a building block in architecture description methods such as arc42. It refers to a piece from which a system is constructed, which may itself be composed of smaller building blocks. Other names for the same concept, chosen by convention within a particular technology stack or level of granularity, include structural element, module, package, namespace, class, or subsystem.