Avians are humans with wings, and are able to fly with said wings, of course. There are all sorts of Avians, and the only limit to wing type is to the bird's wings the species has. Avians have the potential to be able to manipulate wind/air, and usually won't be flying until night so few people are likely to spot them if they look hard enough. Some that have encountered Avians usually say they've seen "Angels" of the sort.
Other names; Winged ones
Avians have certain features that help them fly other than their wings. They have hollow bones like birds, they have a clear layer of skin over their eyes so their eyes don't dry out while flying, and have bigger hearts so that they have more blood flowing through their bodies. They also have air sacs and the reason why they have those is unknown.