Tom Bombadil

In The Fellowship Of The Ring, you all probably remember the light hearted Tom Bombadil, but since rereading the series i have been wondering just who exactly he is. The nearest guess i can make is that he isa Maiar. But thats just a guess from what he says about him self: "but you are young and I am old. Eldest, That's what I am. Mark my words friends: Tom was here before the river and the trees; Tom remembers the first rain drop and the first acorn. He made paths before the Big People, and saw the little People arriving. He was here before the kings and the graves and the Barrow-whites. When the Elves passed westward, Tom was here already, before the seas where bent. He knew the dark under the stars when it was fearless- before the Dark Lord came from Outside". There is also the way that he hones his powers, through song.