Addons (or mods) add new content to your game, such as models, vehicles, weapons, NPCs, tools and more. Addons can be downloaded from the Steam Workshop through the Addons Menu, located in the Main Menu, or through the Steam Workshop website itself, which is also accessible from the Steam Client.
Addons can also be downloaded from 3rd party websites in the form of a folder, which then needs to be placed into your
garrysmod/addons/ folder manually.
Addon related pages: