Meaning – The term plug-in refers to a self-contained software component that modifies (adds or changes) function in a particular software system. When a user adds a plug-in to a software system, the foundation of the original software system remains intact. The development of plug-ins requires well-defined application programming interfaces (APIs).
Plug-ins are commonly used in Internet browsers but also can be utilized in numerous other types of applications.
In popular technologies, like Internet browsers and audio/video applications, the ability to utilize plug-ins makes products more versatile and allows transparent and convenient customization according to the user’s desired features.
Plug-ins also can enable easier software upgrades or patches or additions by project collaborators.
Example of usage – “One plug-in example is the range of customizable options common with browsers like Mozilla Firefox. Users can download individual plug-ins for this free Web browser tool to promote different results on devices.”