These kinds of films often appeal to the emotions of the viewer, with their emphasis on pleasure, physical desire, and human companionship. Films of romance with heart-throb sexy lead characters may have sexual elements, but these are often secondary to the main plot goal - the search and attainment of love. In the days before the film industry's stringent Production Code was established in known as the Hays Code after Will Hays, the head of the Motion Picture Producers and Distributors of America - MPPDA and strictly enforced after to regulate "morally offensive" content, many silent and 'Pre-Code' taboo-breaking films contained adult-oriented material. In addition to nudity, sexuality and violence, they included candid depictions of drug use, prostitution, lawlessness, and religious blasphemy. Since the abandonment of the Hays Code in the late 60s, and the fairly recent establishment of various rating systems, sexual or erotic films with even small amounts of nudity have become more abundant.