In the last book, Snape and Voldemort are seen to be able to fly, after Snape is pushed out of the window in the Hogwarts' classroom. Voldemort flies during his hunt for the owner of the elder wand. How are they able to fly? What is this spell which can enable you to fly, which is stated by the author? (not in Harry Potter Wikia)
I seem to remember there is one such spell known as the Wingardium Leviosa, which lets the person and/or object hit levitate in the air, but this wouldn't be counted as actually flying, just as Snape and Voldemort have done. Does J.K. Rowling ever answer this in any of her interviews?