In a first-person pov, the story is relayed by a narrator who is also a character within the story. First-person can be extremely effective because readers easily identify with it. Some genres utilize first-person extensively, such as Young Adult, Urban Fantasy, and Mystery. A drawback to first-person is you can't hide information from the reader if the character knows it. Usually the first-person character is the one who acts and is the most crucial in the story; also called the major character. This doesn't always have to be the case, we can have minor character narrators, for example, the 2005 novel Spin by Robert Charles Wilson, has an every-man narrator, Tyler Dupree, and has the major character die. A famous example of an unimportant first-person narrator is found in which F. Scott Fitzgerald novel? Hint: It rhymes with Trait Tatsby. :)
In a second-person pov, the narrator refers to one of the characters as 'you', therefore making the reader feel as if he/she is a character in the story. An example is If on a winter's night a traveler by Italo Calvino. The only benefit to second-person is it's unusal. This is also its drawback. Don't do it. (Notice the implied 'you'. Clearly second-person pov is often utilized in blogs. :) )
In a third-person pov characters are referred to as 'he' or 'she'. Notice in this case the narrator is not a character in the story. This pov is the most common and so is the most accepted by readers. It enables authors to withhold facts from readers, makes comments and flashbacks easier to write, gives the author more scope for characterization, and other benefits. Examples include: look on your bookshelf. ;)
There's also the issue of how many pov characters there are, known as singular or plural pov. This can be utilized with any of first, second, and third. (This is not to be confused with multiple povs, e.g. the author could have more than one 3rd person povs.) For example, first-person plural pov would use 'we'. Can you think of any examples of this? Supposedly I, Robot by Isaac Asimov did this. (I'm going to have to check my copy!)
Another significant issue to consider is how close the perspective is to the character(s). An author can utilize an omniscient, a limited/exterior, or an interior/close pov. This is the cinematography of the novel, if you will, WHERE the camera is. The important consideration here is does the reader get to know the character's thoughts and feelings? Is the camera inside the character's brain, so to speak? Or outside, showing a 'just the facts' perspective?
Again, different genres have different conventions here. For example, Young Adult is commonly a very close interior pov; the reader gets to know all the angst-ridden thoughts and feelings of the narrator.
We're starting to get a bit bogged down in possibilities, but I'll add one more: reliability versus unreliability. The unreliable narrative voice involves the use of a non-credible or untrustworthy narrator. Examples? How about Holden Caulfield in The Catcher In The Rye?
These povs can all be mixed and matched in multiple povs! For example, I recently read WWW:WATCH by Robert J. Sawyer and he has multiple third person povs with one first-person pov. The first-person is the artificial intelligence and it does help the reader to identify with him.
So, in summary, I don't know if you've noticed, but we have dozens, if not more, of pov possibilities. I summarize them in a table:
|1st singular||1st plural||2nd singular||2nd plural||3rd singular||3rd plural||interior||.||.||.||.||.||.||exterior||.||.||.||.||.||.||omniscient||.||.||.||.||.||.||reliable||.||.||.||.||.||.||unreliable||.||.||.||.||.||.|
Have fun with it!