When I first started this blog, I did a post on the trouble I had writing in first person. I followed that with a post sharing links to other blogs that discussed the benefits and disadvantages of first person. Admittedly I wrote both of these back when I first started my blog and I was the only person reading it.
Today I'm having another look at point of view and sharing yet more links. Admittedly, I have been avoiding writing in first person since my first ms. I found it way too limiting for extended writing as far as what I could and could not share with the audience. I am going to risk heading back to first person in a couple of months when I start a project I've been thinking about for a long time, but it is only after extended thought and planning that I've chosen to write in first person.
If you want the very brief definition (very-very brief definition) this list of literary terms is quite good as a quick reference guide. It keeps it simple and to the point and is fairly clear.
My own experience has told me that first person is great in the short term if you want to get inside a characters head, but is really difficult to maintain over an entire novel length manuscript because anything your character does not know is really hard to convey to the audience. In a fantasy or sci-fi particularly, it is unlikely your character can explain how everything works, and at times the reader is going to be left a little baffled.
Third person allows the narrator to fill the reader in on a lot of extra information, plus move between characters to where the action is occurring, but makes it harder to show the inner-character. This is how I feel about the styles at least. Feel free to comment and add your own view.
Jeanne of "the Raisin Chronicles" gives her own definitions of point of view and examples. Well worth a read.
K.M. Weiland of "Wordplay" has a list of reference books that have pretty much everything on writing, including one that looks at plot structure and point of view.
Nathan Bransford also shares his view on the first person or third person debate and some of the comments accompanying this post are well worth the read.