What kind of bird is this?

It's a pigeon. Pigeons come in a wide variety of flavors, and some are bred for show or racing. If you can catch it, see if it has a band on its leg. That would have information about who to get in touch with. It may be tired or ill, so put a bowl of water out for it, and if you have bird food, some of that, and see what it does. If it hangs around, and doesn't have any sort of band on the leg, see if there's a wildlife rehab person near you; those folks usually know about any local pigeon clubs.