What is a short summary of Pride and Prejudice?

In brief, Pride and Prejudice is all about love. The title refers to the main characters, Elizabeth Bennet and Mr. Darcy. The proud Mr. Darcy insults the lively Elizabeth at a ball, saying she's "tolerable" but not attractive enough to tempt him to dance with her.  In return, she develops a prejudice against him and treats him badly. Because she refuses to be nice to him, he falls in love with her. The novel follows the windings and turnings of their relationship, and in the process becomes an examination of different kinds of love.

Elizabeth's kind and beautiful older sister Jane falls in love with Mr. Bingley, Darcy's friend, and Bingley falls in love with Jane, but Bingley, to everyone's surprise, fails to propose to her before leaving for London.

Elizabeth falls for the handsome but unreliable Wickham as Darcy is falling for her. Meanwhile, Elizabeth's fumbling and socially inept cousin, Mr. Collins, proposes to her. She rejects him and is stunned when her best friend, Charlotte Lucas, accepts him. Charlotte, in her own words, is not "romantic," and settles for a comfortable home. When she visits Charlotte, Elizabeth learns that a wise woman can manage admirably with an imperfect husband.

While she's visiting Charlotte, Mr. Darcy proposes to Elizabeth, but manages to wholly insult her by telling her family is horrible and that he split up Jane and Bingley because of it. Elizabeth lets him have it and tells him, essentially, that he's the last person in the universe she would ever marry. Darcy, being proud, had simply assumed she would say yes, so he is stunned.

Elizabeth takes a vacation with her aunt and uncle, the Gardiners, and the three of them stop and visit Pemberley, Mr. Darcy's estate. There, Elizabeth begins to regret giving up being mistress of such a grand place--and to her great embarrassment, runs into Darcy! (She had been told he was out of the area.) He seems to be still very much in love with her. But then bad news comes: Elizabeth's wild younger sister, Lydia, has run off with Wickham without marrying him, a terrible disgrace in that time period. Elizabeth fears the whole family is now ruined, but Mr. Darcy gets the twosome married and saves the day.

In the end, Darcy marries Elizabeth, and Bingley marries Jane. Elizabeth has learned not trust first impressions (the original title of the novel) and the reader learns the importance of marrying based not on a wild passion but on the basis of mutual love and respect.