What constitutes an "adult" film varies by country and rating organization. For example, the British Board of Film Classification (BBFC) uses the category for films featuring: Sexually Explicit Scenes : Depictions of sexual activity.
"Thai food," he agreed, a real, tired smile breaking across his face. Adult Movies
As technology continues to advance and societal norms evolve, the adult film industry is likely to undergo further changes: What constitutes an "adult" film varies by country