Literature is literally "an acquaintance with letters" (as in the first sense given in the Oxford English Dictionary), but has generally come to identify a collection of texts. Nations can have literatures, as can corporations, philosophical schools or historical periods. It is commonly held that a literature of a nation, for example, is the collection of texts which make it a whole nation. The Hebrew Bible, Beowulf, the Iliad and the Odyssey and the American constitution, all fall within this definition of a kind of literature. More generally, a literature is equated with a collection of stories, poems and plays that revolve around a particular topic. In this case, the stories, poems and plays may or may not have nationalistic implications. The Western Canon is one such literature.
Classifying a specific item as being part of a literature (be it American literature, advertising literature, gay and lesbian literature or Roman literature) is very difficult. To some people, "literature" can be broadly applied to any symbolic record which can include images, sculptures, as well as letters. To others, a literature must only include examples of text composed of letters, or other narrowly defined examples of symbolic written language (hieroglyphs, for example). Even more conservative interpreters of the concept would demand that the text have a physical form, usually on paper or some other portable form, to the exclusion of inscriptions or digital media.

Furthermore, there is a perceived difference between "literature" and some popular forms of written work. The terms "literary fiction" and "literary merit" are often used to distinguish between individual works. For example, the works of Charles Dickens are perceived by almost everyone as being "literature", whereas the works of Jeffrey Archer tend to be looked down on as unworthy of inclusion under the general heading of English literature. Works may be excluded if, for example, the standard of grammar and syntax is poor, the story unbelievable or disjointed, the characters inconsistent or unconvincing. Genre fiction (e.g. romance, crime, science fiction) is sometimes excluded from consideration as "literature".

Frequently, these boundaries are crossed by the texts that make up literature. Illustrated stories, hypertexts, cave paintings and inscribed monuments have all at one time or another pressed the boundaries of what is and is not literature.

Forms of literature

Poetry
A poem is a composition usually written in verse. Poems rely heavily on imagery, precise word choice, and metaphor, may be written in measures consisting of patterns of stresses (metric feet), and may be rhymed or unrhymed. It is difficult to characterize poetry precisely. Typically, though, poetry is literature that makes some significant use of the formal properties of the words it uses--those properties attached to the written or spoken form of a word, rather than to its meaning. Metre depends on syllables and speaking rhythms; rhyme and alliteration depend on words having similar pronunciations. Some contemporary poets, such as E. E. Cummings, make extensive use of the visual form of a word.
Poetry is perhaps the oldest form of literature: The Sumerian Epic of Gilgamesh dates from around 3000 B.C.; the Bible and the works of Homer, the Iliad and the Odyssey.

Much poetry is written in specific forms: the haiku, the limerick, the sonnet, for example. A haiku must have seventeen syllables, distributed over three lines in groups of five, seven, and five, and should have an image of a season and something to do with nature. A limerick has five lines, with a rhyme scheme of AABBA, and line lengths of 3,3,2,2,3 stressed syllables.

Some poetic norms are language-specific: Greek poetry rarely rhymes, Italian or French poetry often does, English and German can go either way (although non-rhyming poetry is often, perhaps unfairly, treated as more "serious"). Perhaps the most paradigmatic style of English poetry (exemplified in Shakespeare and Milton) is blank verse: unrhymed iambic pentameter. Some languages prefer longer lines; some shorter. Some of these conventions result from the ease of fitting a language's vocabulary and grammar into certain structures rather than others (for example, some languages contain more rhyming words than others, or typically have longer words). Other structural conventions are historical accidents, resulting from many speakers of a language associating good poetry with a verse form preferred by a particular good poet.

Works for theatre (see below) were traditionally written in verse. This is now rare, although many would argue that the language of drama remains intrinsically poetic.

Drama
A play is another classical literary form that has continued to evolve over the years, comprised chiefly of dialog between characters, usually intended for dramatic / theatrical (see theatre) performance rather than reading. During the eighteenth and nineteenth centuries opera developed as a combination of poetry, drama, and music. Nearly all drama was in verse form until comparatively recently.

Greek drama is the earliest we have substantial knowledge of. The Tragedy developed as a performance associated with religious and civic festivals, typically enacting or developing upon well-known themes in history or mythology. Tragedies were generally very serious in theme and treated important conflicts in human nature, but were not necessarily "tragic" as the word is now used--meaning sad and without a happy ending. Comedy was a later development; Greek festivals eventually came to include three tragedies balanced by a comedy or Satyr Play.

Modern theatre does not in general adhere to any of these restrictions of form or theme. A play is anything written for performance by actors (screenplays, for example); and even some things that are not; many contemporary writers have taken advantage of the dialogue-centred character of plays as a way of presenting literary work that is intended simply to be read, not performed.

Essays
An essay is a discussion of a topic from an author's personal point of view, exemplified by works by Francis Bacon or Charles Lamb. A memoir is the story of an author's life from his personal point of view. An epistle is usually a formal, didactic, or elegant letter.

Prose Fiction
"Prose" denotes writing that does not adhere to any particular formal structures (other than simple grammar); "non-poetic writing," writing, perhaps. The term is sometimes used pejoratively, but prosaic writing is simply writing that says something without necessarily trying to say it in a beautiful way, or using beautiful words. Prose writing can of course be beautiful; the suggestion then is that it is not beautiful in virtue of the formal features of words (rhymes, alliteration, meter), but the distinction does not need to be marked precisely, and perhaps cannot be. There is, of course, the "prose poem," which attempts to convey the aesthetic richness typical of poetry using only prose; and there is the "free verse", which is poetry not adhering to any of the strictures of one or another formal poetic style.

Prose is the normal form of writing for fiction: novels, short stories, and so forth. (The term "fiction" does not normally apply to poetry, even poetry used to tell stories.) All of these exist in occasional scattered form throughout history, but have not developed into systematic and discrete literary forms until relatively recently. Prose works of fiction are sometimes categorized by length. The lines are somewhat arbitrary, since one can write a work with any number of words; yet publishing convention dictates the following: A short story is prose writing of less than 10,000 to 20,000 words (and usually more than 500 words) which may or may not have a narrative arc. A story more than about 20,000 words is called a novella. Beyond that, especially when beyond 50,000 words, a work of fiction is called a novel.

A novel is simply a long story written in prose; yet it is a comparatively recent development. In Europe the first significant novel is perhaps Don Quixote, published in 1600. Yet earlier works, such as the Decameron, the Canterbury Tales have comparable forms, and would probably be called novels if they were written today. Earlier works in Asia, such as China's Romance of the Three Kingdoms" and Japan's Tale of Genji'' by Lady Murasaki, even more strongly resemble the novel as we now think of it.

Early novels in Europe were not, at the time, viewed as significant literature. Perhaps this was because "mere" prose writing was seen as easy and so unimportant. It has become clear, however, that prose writing can be aesthetically pleasing without adhering to poetic forms; and the freedom the author gains in not having to concern himself with verse structure often translates into a more complex plot or one richer in precise detail than is typical of the plots even of narrative poetry. This also frees the author to experiment with many different literary styles--including poetry--in the scope of a single novel.

Other Prose Literature
Philosophy, history, journalism, and legal and scientific writings have traditionally been called literature. They are among the oldest prose writings in existence; novels and prose stories earned the names "fiction" to distinguish them from factual writing or nonfiction, which is what prose has historically been used for.

This has become less so in the case of science over the last two centuries, as advances and specialization have made new scientific research inaccessible to most audiences; science is now published mostly in journals. Scientific works of Euclid, Aristotle, Copernicus, and Newton still possess great value; but since the science in them is largely outdated, they can no longer be used for scientific instruction, yet they are too technical to sit well in most literature programmes. They are now read less and less outside of history of science programmes. There are a number of books "popularizing" science which might still deserve the title "literature"; history will tell.

Philosophy too has become an increasingly academic discipline. This is lamented by more of its practicitioners than was the case with the sciences; nonetheless most new philosophical work is done in academic journals. Major philosophers through history: Plato, Aristotle, Augustine, Descartes, Nietzsche--have become as canonical as any writers can be. Some contemporary philosophy undoubtedly merits being called "literature"--the work of Wittgenstein, for example; but much of it does not, and some areas, such as logic, have become extremely technical to the same degree as the sciences.

A great deal of historical writing can still be called literature, particularly the genre known as creative nonfiction as can a great deal of journalism, literary journalism. However these areas have become extremely large, and often their purpose is just utilitarian: to record data or convey immediate information. As a result the writing in these fields is not as a rule literary, although it often and in its better moments is. Major historians include Herodotus, Thucydides, Procopius, all of whom are considered canonical literary figures. Law is a less clear case. Some writings of Plato and Aristotle, or even the early parts of the Bible, might count as legal. The law tables of Hammurabi of Babylon might count. Roman civil law was codified during the reign of Justinian I of Byzantium, and this is considered significant literature. The founding documents of many countries, including the Constitution of the United States, are treated as literature, howver legal writing is rarely noted now for its literary merits.

Most of these fields, then, through specialization or proliferation, no longer generally constitute "literature" in the sense under discussion. They may sometimes be "literary literature"; more often they are what might be called "technical literature" or "professional literature."

Somewhat Related Narrative Forms
Comics are stories told in a combination of sequential artwork,dialogue and text.