In BDSM, a switch is someone who participates in BDSM activities sometimes as a top and other times as a bottom or (in the case of dominance and submission) sometimes as a dominant and other times as a submissive. Switches are very common; partners may switch roles based on mood, desire, or to allow each partner to experience their preferred activity. For example, a switch may be in a relationship with someone of the same primary BDSM orientation (e.g., two dominants), so switching provides each partner with an opportunity to realize his or her BDSM needs.