Literature is, as has been pointed out in this discussion, not simple to define. I tend to agree with the overall notion presented above: literature is using language artistically.
There is a good deal of subjectivity involved in deciding what constitutes art and artistry and within the arena of "literature at large" there are attempts at even finer distinctions between forms of writing.
The literary novel is a special form of the novel, distinguished from "pulp fiction" or "genre fiction", defined by its aims at being literary art as opposed to literary entertainment.
Generally speaking, we might say that art is an attempt at the expression of something true of the human condition. Maybe that's a bit vague, but it can serve to divide art from entertainment.
Literature is the recording of the human experience, an exploration into the human heart and soul. Thus, it evokes feelings and thoughts from its readers who enter into true communication with the literary work. Whosoever reads literature with such an open heart comes away fuller.
One of the best and simplest definitions I've encountered is that literature is any use of language in which words call attention to themselves AS WORDS. For example, when we read the newspaper we generally read for information, facts, and opinions. As soon as we start paying attention to the skill with which a something is written, we are starting to treat that piece of writing as literature.
One of the best books on this topic remains, in my opinion, Theory of Literature, by Wellek and Warren. John M. Ellis has also written a very fine book on this topic.
I, also, agree that the definition of literature is subjective. As wannam points out, the technical definition of literature is "the art of written words." That being said, some may not find the work of the Marquis de Sade as literature (based upon the definition). Others may. Therefore, like art, what one finds to be literature is purely subjective.
The technical definition of literature is "the art of written words" (http://en.wikipedia.org/wiki/Literature). Of course, art is a highly subjective term. I might think a group of words is an artful poem while someone else might think that same group of words is nothing more than random babble. There are certain elements within literature that are generally agreed upon. There are also certain forms of literature that most people recognize. However, there are plenty of works which may or may not qualify as literary art.
I agree that defining literature is highly subjective. For me, there is a temporal element in that subjectivity. Will it last? Or is it just a trendy piece of work? We cannot always judge this in our own time. I also think there must be some sort of universality for a work to be literature, some way of allowing us to see something beyond ourselves. If my mind is not expanded, it cannot be literature.
Actually, the definiton of literature can be subjective. An objective definition might consider any written product literature if it is in the basic forms: novel, poem, or play. It gets a little more interesting with nonfiction, but there are definitely pieces of nonfiction that are considered literature. The subjective definiton of literature assigns value. Only high quality writing is literature, in that case.
Literature is a term used to describe written or spoken material. Broadly speaking, "literature" is used to describe anything from creative writing to more technical or scientific works, but the term is most commonly used to refer to works of the creative imagination, including works of poetry, drama, fiction, and nonfiction.