Regency Romance
Regency Romance is the title given to the sub-genre of traditional romance novels that are not just set in Regency times, but also have their own rules. The books concentrate on traditional story lines, e.g., marriages of convenience, arranged marriages, nanny and/or governess romances. Although there is sexual attraction and tension, there is usually no sex between the unmarried hero and heroine. Often the writing is more formal or stylized. The books are usually shorter and distinctive from other "full-length" historical books which are also set in the Regency period.
In the past all publishers had a line of Regency books. In 2005, some publishers (Zebra) stopped publishing traditional Regencies. See the article at All About Romance.
Authors of the Regency period, such as Jane Austen were the first to write what might be considered Regency romances. Some herald Georgette Heyer as the first, and perhaps the greatest, of the modern Regency authors. What these books have in common is the attention paid to the manners of the day and the interaction of the characters.
Many authors got their start with Regencies and then moved on to other genres. For example, Stephanie Laurens began with Regencies and then began writing full-length historicals. Others are Jo Beverley, Loretta Chase, Mary Balogh and Mary Jo Putney.