1. You all know a patronus, right?
(HINT: It’s that thing in Harry Potter …)
3. This is a patronus, according to the Harry Potter Wiki:
The Patronus Charm (Expecto Patronum) is an immensely complicated, very difficult spell that evokes a partially-tangible positive energy force known as a Patronus (pl. Patronuses4) or spirit guardian3. The charm was primarily designed for defence against Dementors and Lethifolds, against which there is no other protection5. Albus Dumbledore, however, invented a means of using one’s Patronus as a messenger to other witches and wizards, and this is the method of communication that the Order of the Phoenix uses3.