Minecraft Adds Official Mods This Month As A Test, Third-Party Mods Still Supported

Mojang said fans can think of add-ons as mods in that they 'change the way that things in the game look and behave.'

Players can sideload mods from third-party sources as much as they want, provided these mods remain in compliance with the Minecraft End-User License Agreement (EULA).

Read at GameSpot