Romantic fiction novels are available in a variety of sub-genres, including historical romance, science fiction, and science fiction. Other divisions in this genre include romance books geared toward teenagers, fiction written for certain ethnic markets, and books that contain religious themes. These sub-genres often have their own sub sub-genres, such as American Western or Regency period novels as a subset of historical romance. Some publishing houses specialize in one type of romantic fiction, while other publishers choose to offer several different sub-genres to their customer base.
In some cases, romantic fiction may incorporate other fiction genres, such as mystery, fantasy, or science fiction. For example, one genre of fiction that has been popular in the 21st century so far has been the fusion of vampire fiction with romantic stories. In other cases, the romantic story may be paired with stories of ghosts or other supernatural beings in fantasy novels. Romantic novels may also contain erotic writing, though many sharply limit description of intimate contact between characters.
Some romantic fiction is distinguished by being set in a particular historical period. While contemporary romantic fiction is set at the time in which it is published, many authors choose to focus on writing stories that take place during a particular point in history. In many cases, these authors also keep their stories set in a particular geographical region. One particularly popular sub-genre is that of Regency romances, which are typically set in Great Britain during the Regency period. In these books, the authors typically take great pains to describe the customs and etiquette of that period, and in some cases the characters may bear titles of nobility or even royalty. The historical accuracy of these novels is sometimes questionable, though some historical romance writers make a point of depicting the social concerns of the period.
Romantic fiction may also be geared toward particular age groups and religious affiliations. For example, teen romance novels are very popular in many places, and many of romantic fiction sub-genres have their own teen version sub sub-genres. Similarly, romantic fiction may also be written in a way that reflects a particular set of religious values, with so-called inspirational romance books carrying a an explicitly religious theme even as the books belong to typical romance sub-genres such as historical romance or mystery/suspense. Another popular twist on the religious sub sub-genre involves the situation of a story within a secure religious community, such as the Amish.