This section goes over general information that is useful to both plugin and theme developers alike. For more details on either one visit their respective pages.
Currently, BetterDiscord only supports two main types of addons: Plugins and Themes. They serve as the main way to personalize and control your own client. All addons are required to provide certain meta information, which you can learn more about on the addon system page.
Themes are exactly as they sound, a way to completely alter the look and feel of the client. Some themes might just add a background image to the client, while others try to emulate the look and feel of other programs, or even other operating systems. They do this by using pure css like a webpage as opposed to using preset names that limit the creativity of developers. To read more about making them, check out the plugin documentation after finishing this section.