Since most Minecraft mods are created by the general public, particularly by Minecraft hobbyists, many mods can be downloaded from the Mods section of the Minecraft Forum page for free. The site has a large collection of mods as well as comments and reviews from other users that reveal which mods work and which are problematic. The Minecraft Wiki also has an extensive collection of mods, some of which include installation information.
Minecraft modding alters the way Minecraft behaves by changing the game files. These alterations range from creating new blocks to completely overhauling the way the game is played.
Most mods involve manipulating the game's folder structure. Since fiddling with the game's folder structure can cause problems, it is important to back up files like the Minecraft save folder. However, should the modding can corrupt the game completely, a clean copy of Minecraft can always be downloaded again from the game website.
Forge and Modloader are two of the most important Minecraft mods, but they do not enhance or alter the game mechanics by themselves. Instead, they make installing mods less complicated. Forge is the more popular of the two, and it is updated to version 1.8 of Minecraft as of June 2015.