Running a module.
Mods, or Modules are installable content packages for the Mount&Blade series of games.
Mods can consist of minor changes or additions to the game, to an all out reworking of the Native module (the default game itself). They can be downloaded from various websites, many of which specialize in just that. These mods usually follow certain themes, decided upon by their creators. Mods are ultimately limited only to their creators’ imagination and knowledge of how the game is put together.
Ease of Use
One of the aspects of the Mount&Blade series is the ability to easily install modules into the game. The creators of Mount&Blade embraced the idea and designed a module editing script, accessible by enabling "edit mode" from the splash screen and hitting ctrl-e in game.
Mod Themes
There are Star Wars mods, post-nuclear war mods, civil war, and western mods, just to name a few. Googling, "Mount & Blade mods" will literally bring up hundreds of mods available for download, and TaleWorlds gives detailed instruction, tools, and forums for insight in developing your own modules for Mount&Blade.
Modding Tools
There exist no official modding tools for Mount&Blade currently, however, the developers have stated that such tools will be provided and freely usable to make mods for Mount&Blade II: Bannerlord.
Unofficial modding tools have been made by the modding community.