 Within the general class of pornography, so defined, there is enormous variety in content. For example, some material depicts women, and sometimes men, in postures of sexual display (e.g., Playboy centerfolds). Some depicts non-violent sexual acts (both homosexual and heterosexual) between adults portrayed as equal and consenting participants. Feminist pornography is a subset of pornography (in this general sense) that aims to subvert traditional gender roles, bodies, and narratives unreflectively endorsed by mainstream heterosexual pornography. Other sexually explicit representations depict acts of violent coercion: people being whipped, beaten, bound, tortured, mutilated, raped and even killed. Some sexually explicit material may be degrading without necessarily being overtly violent. This material depicts people (most often women) in positions of servility and subordination in their sexual relations with others, or engaged in sexual acts that many people would regard as humiliating. Some sexually explicit material involves or depicts children. Some portrays bestiality and necrophilia; and so on. Researchers often distinguish between ‘hardcore’ and ‘softcore’ porn; ‘egalitarian’ and ‘inegalitarian’ porn; or between ‘violent’, ‘non-violent and degrading’, and ‘non-violent and non-degrading’ pornography, since different types of pornography may be harmful to different degrees and in different ways.