A romance novel primarily focuses on the relationship and romantic love between two people. They almost always have an emotionally satisfying, optimistic ending. Bestselling author Nora Roberts has said "The books are about the celebration of falling in love and emotion and commitment, and all of those things we really want." There are books about love that are not romance novels, and what precisely qualifies as a romance novel is usually determined in part by the publisher of a book.

Romance can be broadly divided into category (series) and stand-alone (single title). Category romances in many cases are numbered sequentially within the line. Category romance lines are usually no more than 200 pages. Despite their name, single-title novels are not always stand-alone novels. They are almost almost longer, averaging between 350 and 400 pages.

Romance subgenres include gothic, historical romance, paranormal romance, western, regency (dealing with royalty), romantic mysteries, romantic suspense, fantasy/sci-fi romance, inspirational, adventure, and contemporary romance. In other words a romance novel can be set in any time period and in any location.

The best selling romance novels of all time are: (1) The Phantom of the Opera by Gaston Leroux; (2) The Notebook by Nicholas Sparks; (3) Dark Hunter by Sherrilyn Kenyon (series); (4) Twilight by Stephenie Meyer (series); and (5) It Had to Be You by Susan Elizabeth Phillips.

Best selling authors in the romance genre by estimated sales over 100 million are: (1) Barbara Cartland; (2) Danielle Steel; (3) Jackie Collins; (4) Corin Tellado (Spanish language); (5) Janet Dailey; (6) Nora Roberts; and (7) Catherine Cookson.