How films are catagorised in movie rental places.
A grouping based on shared similar characteristics.
In theory genre exists for convenience, allowing people to identify broad groups without having to name specific titles from within the group.
In other words, you can decide on a film to rent without having to go through reading the back of each and every box.
Often however there are discrepancies with the categorisations, particularly as the boundaries between genres can be quite fluid. In practice this means genre categories can be less than helpful.
The term also applies to other media such as music, books, theatre and art.
Examples of film genres could include: Action, Comedy, Drama, Romance, Kids, Horror, Science Fiction.