Quote Originally Posted by lankybugger View Post
I've never actually played The Elder Scrolls... What do Soul Gems do?
Pretty much this. You cast Soul Trap on an enemy, capture its soul in a gem, and use that as the power source when crafting a new magical item. The stronger the foe, the more potent the power source; it requires a very strong foe to create an always-on effect or to create an item with enough charges to unleash powerful short-term effects.