Modules are objects that apply certain buffs to your towers, troops, technologys, or heros. There are 3 types of modules: Common, 1 buff, Rare, 2 buffs, and Legendary, 3 buffs. Aquiring 2 of the same module allows you to fuse it. Therefor increasing it's level by 1 and increasing its buff by 10%. You can also sell any useless modules for Antimatter.