Mod

A custom game component that alters gameplay; includes examples such as DotA (Defense of the Ancients), a popular Warcraft 3 mod, Counter-Strike, a mod of Half-Life, and user interface mods for World of Warcraft.

A mod is a moderator for an Internet forum, online game, or discussion. The mod regulates the activity that occurs within the space, which includes the pace, tone, and content contributed by participants.

Mod is simply an abbreviation of "moderator" that many online users find helpful when referring to the moderator role. Being a mod is a big responsibility because much of the success and helpfulness of the game or discussion relies on the mod's abilities.

The mod of a discussion, game, forum, etc. is usually appointed beforehand to allow for preparation. Typical mod responsibilities include the welcoming of participants, the introduction of yourself, laying the ground rules, and regulating content posted/shared by participants according to the rules, responding to feedback, and closing the shared time together when there's a time limit.