gecko/addon-sdk/source/doc/module-source/high-level-modules.md

High-Level APIs

Modules in this section implement high-level APIs for building add-ons:

• creating user interfaces
• interacting with the web
• interacting with the browser

Unless the documentation explicitly says otherwise, all these modules are "supported": meaning that they are relatively stable, and that we'll avoid making incompatible changes to them unless absolutely necessary.