MinecraftForge v9.11.1_965 for Minecraft 1.6.4Released: Nov 21st, 2013
MinecraftForge (aka. Forge, Forge ModLoader) is a mod developed for Minecraft that makes it easier to install other mods.
Minecraft itself does not have support for mods built in. Despite that developers around the world found a way to open up the game and add in new functionality. In the beginning, it was really difficult to add these first mods to your gahat me. You had to open up source files, copy some things, delete some things and in the end hope that it all worked.
The crew behind MinecraftForge decided that if they could make a common API (application programming interface) for other developers, it would be much easier to add mods to Minecraft. The end result is that MinecraftForge makes it super easy to install and manage mods in the newer versions of Minecraft.