1 - General romance. Kissing is allowed but, in the nonpassionate sense. This type of romance is labeled as sweet because they are just that... sweet and nothing more.
2 - Passionate kisses and touching is allowed, but physical romance is more implied and not really shown to the reader. This story would focus more on emotions and there should be no graphic sexual description.
3 - This is a sensual story on the very low spectrum of erotic romance. Passion and a physical relationship may be shown to the reader but, in a more tasteful and less graphic manner. While you may describe things for the reader, things should be described so that the reader can envision and imagine their connection without having to tell them.
4 - This story will not sugar coat anything for the reader. Explicit sensuality and a physical relationship should be an important role in the story. This level of heat should have at least 2 sex scenes, with at least one scene including intercourse. Menage, BDSM, fetish or any other type of play which doesn't center around the two main characters would not fit under this heat rating.
5 - A level 5 story will center around a strong physical relationship with a minimum of 3 sex scenes (with at least one being intercourse) between the main characters. Menage, BDSM, fetish or any other type of play which doesn't center around the two main characters would fit under this heat rating.