Erotica is art, literature or photography that deals substantively with subject matter that is erotic, sexually stimulating or sexually arousing. Some critics regard pornography as a type of erotica, but many consider them to be separate. Erotic art may use any artistic form to depict erotic content, including painting, sculpture, drama, film or music. Erotic literature and erotic photography have become genres in their own right. Erotica also exists in a number of subgenres including gay, lesbian, women's, monster, tentacle and bondage erotica.