All add-ons for openHAB 2 are part of the distribution. This includes all new 2.x bindings as well as all 1.x add-ons that were reported to be compatible. Add-ons can be easily installed through the Paper UI (menu entry "Add-ons").
Bindings integrate physical hardware, external systems and web services in openHAB.
System integrations expose openHAB to external systems.
Actions are predefined methods for openHAB rules and scripts.
Persistence services allow openHAB to store time series data for history-based actions or statistics.
Transformations are used to translate between technical and human-readable values for items.