Dystopian literature is a type of literature that has stemmed from utopian literature. Both are taken from St. Thomas More's book Utopia, which is largely based on ideas introduced in Plato's Republic. Utopia is, simply, a perfect civilization based on equality and self-government (i.e. no/few laws, war, etc.). Dystopia, occasionally called anti-utopia, cacotopia, or kakotopia, is simply the opposite of utopia. It's society could have the appearance of perfection superficially, strategic social oppression (in the form of a rigid caste system or similar), governmental domination over everything from societal norms to economic situation, use of distraction (war, poverty, etc.) to keep citizens from rebelling against or criticizing society, use of sensory images and mass social dillusion/oppression to bringing citizens to believe their society is perfect, and/or extremely spartan military and police occupation, among other things.
Most dystopian literature takes place in a future or alternate time, relative relation to society today, and an outsider/rebel protagonist eventually escapes/changes society/is eliminated/conforms.
Some examples of dystopian literature: Brave New World and Ape and Essence by Aldous Huxley, Atlas Shrugged by Ayn Rand Fahrenheit 451 by Ray Bradbury, The Handmaid's Tale by Margaret Atwood, 1984 (alternately called Nineteen Eighty-Four) by George Orwell, Jennifer Government by Max Berry, The Machine Stops by E.M. Forester, A Clockwork Orange and 1985 by Anthony Burgess, The Time Machine by H.G. Wells, This Perfect Day by Ira Levin, Utopia X by Scott WIlson, The Iron Heel by Jack London, "Harrison Bergeron' by Kurt Vonnegut, Fatherland by Robert Harris and We by Yevgeny Zamyatin.
Also see: graphic novel, cyberpunk, dystopia
Just to let you know, I didn't put this under dystopia because I wanted to talk specifically about liturature. It is technically incorrect to place this article under dystopia because dystopia is not only a type of liturature.