One of the major themes of Jane Austen's Pride and Prejudice is that of wealth and social class.
Note that the Industrial Revolution plays a large role in shaping the society in which Austen sets the story. For many years there had been a wide separation between the poor and upper-class; the advent of wealth earned through trade created a strong middle-class in England. People, for example, who raised sheep, were able to earn money through trading English wool which was preferred over wool from the Continent. English wool became desirable in other countries, and the sheep farmer became a wealthy member of the emerging middle-class. Still dismissed by the aristocratic element of society—for his rough manners and his "new" money, the middle-class merchants also became objects of resentment in that they often possessed more money than many members of the aristocracy—who lived "large" and spent money that was not easily replaced.
It becomes evident early on that wealth and station have a great deal of bearing on Austen's presentations of certain characters. Lizzy (our protagonist) is from a family of the middle-class gentry. Their money comes from work, not from "old money" passed down through one's family.
One of the snobs in the story is Lady Catherine De Bourgh, who is accustomed to the obeisance (deference due to her station) from others. She seems to have no redeeming qualities. Others are the Bingley sisters, using social status against Lizzy because of their jealousy for her.
On the other hand, Fitzwilliam Darcy is also of the upperclass—he is handsome, sophisiticated, and "filthy rich." His reputation is not a good one with the gentry at the start of the story:
...he was discovered to be proud, to be above his company...
Lizzy overhears him making disparaging remarks about her at a dance and takes an immediate dislike to him...
[Darcy] looked for a moment at Elizabeth...and coldly said, “She is tolerable, but not handsome enough to tempt me...”
The inference in the story is that Darcy has little time for those of the lower classes, and those who don't meet his high standards.
Lizzy's resentment is so great that she foolishly believes what the rogue, Wickham, says of Darcy—simply because she dislikes Darcy on "principal"; she forgoes her usual good sense and believes the worst of Darcy.
Darcy is something of an enigma. Though rich, handsome and proper, he has little patience for the foolishness of his peers, and will not engage in what he believes to be frivolous behavior. He is not "warm and fuzzy" with others, which makes him seem cold and unfeeling.
Because of his natural dignity and contempt for vulgarity, his reticence makes him appear haughty...
However, it is Darcy that pays Wickham's debts (although Wickham is his enemy) to save Lizzy's sister, Lydia, when she foolishly runs off with Wickham. Darcy discovers a desire to be more thoughtful—looking to the best interests of others, and overcoming his dismissive behavior of those who are of a lower "rank" than he.
Lizzy soon finds that a decent man lurks beneath his "haughty" facade, and gives him a chance to redeem himself. He expresses respect for her family, another step that shows he can dismiss class delineations, and he humbles himself to be guided with regard to marriage based on Lizzy's desires, and she accepts his proposal.
Though class and money play a strong part in the novel, Austen allows that love and respect can break these social barriers.