Genre

According to Wikipedia, genres are formed by conventions that change over time as new genres are invented and the use of old ones are discontinued. Often, works fit into multiple genres by way of borrowing and recombining these conventions. While the scope of the word "genre" is commonly confined to art and culture, it also defines individuals' interactions with and within their environments. In order to be recognized as genre these interactions and environments must be recurring.

The concept of genre originated from the classification systems created by Aristotle and Plato. Plato divided literature into the three classic genres accepted in Ancient Greece: poetry, drama, and prose. Poetry is further subdivided into epic, lyric, and drama. The divisions are recognized as being set by Aristotle and Plato; however, they were not alone. Many genre theorists contributed to these universally accepted forms of poetry. Similarly many theorists continued to philosophize about genre and its uses, which caused genre as Plato and Aristotle knew it to evolve and further expand.

In 1984, Carolyn Miller examined genre in terms of rhetorical situations. She claimed that "situations are social constructs that are the result, not of 'perception,' but of 'definition'". In other words, we essentially define our situations. Miller believes genres are created through social constructs.

Read more about genre from Wikipedia

Honestly I do not believe genre can be learned from a book, a teacher, or in a classroom. The only way to really understand the genres of a particular discourse community is to study the genres in action. This means looking at documents created within the community and talking with the writers (and recipients) about how those documents work (and don't). In many ways, real genre awareness only comes through immersion in the discourse community and interacting within it.