Angels are spirits that are stronger than regular spirits, but aren't god level either. Angels is an umbrella term, as there are in fact many different kinds of Angels. Most Angels serve under a god or multiple gods, but there are some Angels that keep to themselves and don't associate with gods. These are known as 'Fallen Angels', even though they normally don't have a physical form. Angels can (temporarily) turn into a physical form, which may or may not reflect that of their spiritual form. These transformations usually only last for a week before the Angel absolutely needs to turn back to recharge energy.
Angels are masters of magic, able to cast a variety of strange and incredible spells. These include many things, such as sealing spells, casting auras, and the interesting Develri Spell. These beings can do pretty much whatever they want, although nearly all of them are good. There are a few Angels who follow darker and more sinister gods that are evil and full of malice, but these aren't very common. It is easy to get confused between the two, since Angels have a wide variety of types and forms and since they are strange and can be hard to understand.
Angels have a tendency to be weird and somewhat song-like in their voices and tend to be rather graceful fellows. These beings also are normally enigmatic and, sometimes, can spontaneously change emotion. They're very unpredictable and may not understand mortal concepts, such as a fear of death or illness. They do have separate personalities for each one (except for some who basically have a hive mind with other Angels of their kind), and have fully functional emotions and everything, just like sentient species. However, Angels are not formed when someone dies, as some are mislead to believe. Angels can only be formed by a god, who gives the Angel form and life in turn for their devotion.