A mistress is a term used to describe a female dominant and falls under the BDSM umbrella. A mistress has consensual slaves and/or submissive who can be of any gender or sexuality. The role of a mistress is to direct and control the slaves and/or submissive. This can consist of humiliation, forcing house chores and even consensual physical abuse such as spanking.
For many mistresses and submissive the role can consist of being either sexual and non-sexual. It is noteworthy that many people enter into a mistress/submissive relationship with no be controlled in a non-sexual manner.