Didacticism is an artistic philosophy that emphasizes instructional and informative qualities in literature and other types of art. Didactic art should not primarily "entertain" or pursue the subjective goals of the artist.
An example may be found in Alexander Pope's An Essay on Criticism, which offers a range of criticism and advice.
The term "didactic" also refers to texts (and by extension, media, such as film or television) that are overburdened with instructive, factual, and/or otherwise "educational" information, sometimes to the detriment of a reader's (or viewer's) enjoyment. The opposite of "didactic" is "non-didactic." If a writer is more concerned with artistic qualities and techniques than with conveying a message, then that piece of work is considered to be non-didactic, even if it is instructive/educational.
Some have suggested that nearly all of the best poetry is didactic. Contrarily, Edgar Allan Poe called didacticism the worst of "heresies" in his essay The Poetic Principle.
A good example of didactism in music is the chant Ut queant laxis, which was used by Guido of Arezzo to teach solfege syllables.