A plugin is a script or set of scripts that changes Vim's default behavior, either by adding non-existing features or by extending existing features.
Often added "non-existing features" include:
- commenting,
- indentation detection,
- autocompletion,
- fuzzy-matching,
- support for a specific language,
- etc.
Often extended "existing features" include:
- omni-completion,
- text-objects & motions,
- yanking & putting,
- status line,
- search & replace,
- buffer/window/tab page switching,
- folding,
- etc.