The concept of genre is as old as literary theory itself, but centuries of debate haven't produced much consensus on the topic. Part of the reason is that genre looks like a different thing at different points in the life of a text. Scholars of rhetoric tend to focus on the patterns of communicative action that produce memoranda or tragedies. Sociologists are sometimes more interested in institutions that organize reception. Literary scholars, for their part, have traditionally been preoccupied with the patterning of the texts themselves. Of course, all of these aspects of genre are connected. But it's not easy to describe the connections.