What point of view is employed in the novel the Great Gatsby?1st person 2nd 3rd,t

I'll add a few things as well, concerning narration in
The Great Gatsby. 

First, almost all
fiction is told in the past tense.  Very little fiction uses present tense and tries to
make readers pretend that the story is occurring simultaneously with their reading of
it.  It just doesn't work well.

Telling a story in the past
tense, after the events have occurred, doesn't make for a story told in flashback. It
makes for a story told in past tense.  Nick's narration is no different from most other
fiction in this respect.  He openly talks about the fact that he is writing about the
events after they've occurred, but that doesn't make the story
flashback.

A flashback reveals occurrences previous to the
present in the novel.  When Nick describes Gatsby's pursuit of Daisy five years before
the novel opens, he is using flashback.  The entire novel is not flashback,
however.

To add to what you know about the first-person
point of view, Nick is an unreliable narrator.  That is always a possibility with any
narrator, but especially with a first-person
narrator. 

Nick makes a point to inform the reader at the
beginning of the novel that he is objective and doesn't judge people.  He uses an
anecdote to explain to the reader that his father taught him to not judge people,
because others didn't necessarily have all the advantages that he had.  Nick emphasizes
that he always tries not to judge people.

Of course, this
shows that he often judges people.  You don't have to excuse people for their
backgrounds if you don't judge them negatively to begin with.  And you don't have to
concentrate on not judging people, if you don't judge
people.

And Nick often judges people.  He condemns Tom
immediately, the first time he describes him, going back to his days at Yale with him. 
He also judges Jordan when they first meet.  He makes value judgments throughout the
novel.