软件由无数个plug-ins组成,或曰a plug-in是软件的一个组成部分。
In computing, a plug-in (or plugin) is a set of software components that adds specific abilities to a larger software application. If supported, plug-ins enable customizing the functionality of an application.
Software extensions differ slightly from plug-ins.
An extension is a file containing programming that serves to extend the capabilities of or data available to a more basic program. It is a kind of list of commands which are directly included in the program. This term often (mistakenly) coincides with the plug-in. When installing software, you may be instructed to take one or more steps related to installing extensions (or these steps may automatically be done for you).
An add-on is a software extension that adds extra features to a program. It may extend certain functions within the program, add new items to the program's interface, or give the program additional capabilities.
Add-on is often considered the general term comprising snap-ins, plug-ins, extensions, and themes.