Narrative theory analyzes how media texts communicate meaning about events through stories. Several theorists have contributed concepts to narrative theory, including Propp who identified character archetypes, Todorov who described narratives as moving from equilibrium to disruption to new equilibrium, and Barthes who identified five codes that make up narratives. Levi-Strauss introduced the concept of binary oppositions in stories, such as representing good as civilized and bad as savage. Genre theory categorizes films by type and studies them as members of genres rather than as unique works. Theorists Buckingham and Altman noted that genres are not static but evolve through negotiation, change, and hybridization with other genres over time.