Defining Genre

Genre does not rely simply on what's in a media text but also on the way it is put together (constructed). This can be important, for example, when distinguishing between a horror movie and a thriller, which can deal with similar subject matter, and look the same — lots of action set at night — but belong to separate genres (a horror film takes the audience into a supernatural place, where a thriller sticks to reality).
A media text is said to belong to a genre, as it adopts the codes and conventions of other texts in that genre, and lives up to the same expectations. Texts from different mediums may belong to the same genre.