Writing theorist James Britain suggests that all writing is expressive. Viewed this way, writing means using language to develop articulate thought, to push our inchoate inner speech into meaningful words and sentences . . . to "express" ourselves (from Latin exprimere: ex "out" + premere "to press"). Writing is thereby the process of learning in action. To paraphrase novelist E.M. Forster, how do we know what we think until we see what we write?
We can classify the writing that results in two ways. One way is by the degree of formality, and the other is by the writing's purpose.