Literature broadly is any collection of written work, but it is also used more narrowly for writings specifically considered to be an art form, especially prose fiction, drama, and poetry. In recent centuries, the definition has expanded to include oral literature, much of which has been transcribed. Literature is a method of recording, preserving, and transmitting knowledge and entertainment, and can also have a social, psychological, spiritual, or political role.
Literature, as an art form, can also include works in various non-fiction genres, such as biography, diaries, memoir, letters, and the essay. Within its broad definition, literature includes non-fictional books, articles or other printed information on a particular subject.Etymologically, the term derives from Latin literatura/litteratura "learning, a writing, grammar," originally "writing formed with letters," from litera/littera "letter". In spite of this, the term has also been applied to spoken or sung texts. Developments in print technology have allowed an ever-growing distribution and proliferation of written works, which now includes electronic literature.
Literature is classified according to whether it is poetry, prose or drama, and such works are categorized according to historical periods, or their adherence to certain aesthetic features, or genre.
The following paper entitled Resource Letter: The Nature and Status of String Theory was authored by Donald Marolf
at UCSB. It gives a useful annotated overview of string theory literature, both popular and technical.
http://xxx.lanl.gov/abs/hep-th/0311044