This guide is about Destiny 2 mods. The game, sequel to 2014 Destiny game, is coming out for PC in Oct 2017. There are new mods in the game allowing you to introduce new effects and power to your gear. Mods can add new abilities and Power Level to Legendary and Exotic weapons and armour. This guide will explain these mods in the game.
You can get mods from these sources.
Install mods the same way as infusing. Mods are one-time use items only so if you use a new mod, it will overwrite and delete the old one.
Mods are useful to add Power Level to Legendary Gears. When you reach Power Level 280 and can acquire Legendary Gear easily, mods become very useful. Trade your regular Rare mods with Banshee-44 to acquire legendary mods. When infusing, mods are also taken into consideration but only on the gear you are infusing to.
Hence, its worth to keep as much Legendary Gear with mods as possible. This is a part of the endgame grind to reach the maximum possible level cap.