What is Literature?

Merrian-Webster Online Dictionary: Writings in prose or verse; especially: writings having excellence of form or expression and expressing ideas for permanent or universal interest.

The Free Dictionary (Online): Written material such as poetry, novels, essays, etc., especially works of imagination characterized by excellence of style and expression and by themes of general enduring interest.

L&L Course Companion p.9: A highly developed use of language in that is the stylized manipulation of language for larger effect (purpose) and/or affect (emotional response) 

2 of these definition say "Written". So we can make a difference between language and literature that would be that language is spoken and literature is written, but, what other concepts are relationated with Literature. We have poetry, novels, essays; also prose, verse.

So in Literature we have Form and Background, how do we express something, that has to be always written but there is where porse and verse are. And what do we express, it can be emotions, situations, critics, etc. Literature is all the written things, it includes form and background.