Every time you loot an item from a boss there is a chance the item will receive a random enchant. Each enchant has a random chance to give a wide range of different stats and values. So remember to always at least greed roll on an item! It could give you a really great stat... but lets face it, you'll probably get a bad stat because of that hidden -69 Luck buff you have.
The most common enchants are colored green and only have one stat that ranges from 10 to 50 for primary and secondary stats. 100 to 500 for spell and attack power.
You can also have a chance to loot a more rarer enchant which is colored blue and will offer you two random stats instead of one!
Further more you have a additional chance to recieve both a common and rare enchant on an item!
Rumors are there is even a 3rd additional chance to recieve a really rare enchant as well! But you know how rumors are...!?