What is Plug-in?

A plug-in (or plugin, add-in, addin, snap-in) is a software component that adds a specific feature to an existing software application. When an application supports plug-ins, it enables customization. Plug-ins are commonly used in web browsers to play video, scan for viruses, and display new file types. They are also used in software like image editors and audio players to add features like new effects or file format support.