The three most important aspects of The Great Gatsby:

Nick Carraway is the narrator, or storyteller, of The Great Gatsby, but he is not the story’s protagonist, or main character. Instead, Jay Gatsby is the protagonist of the novel that bears his name. Tom Buchanan is the book’s antagonist, opposing Gatsby’s attempts to get what he wants: Tom’s wife Daisy.
From the gold hat mentioned in the novel’s epigram to the green light at the end of Daisy’s dock, The Great Gatsby is filled with things that are gold and green: the colors of money.
There are two kinds of wealth in The Great Gatsby: the inherited wealth of Daisy and Tom Buchanan, and the newly acquired wealth of Gatsby. The first kind comes with social standing and protects the Buchanans from punishment, as Daisy literally gets away with murder. Gatsby’s kind of wealth, though considerable, leaves its owner vulnerable.