Literary criticism records opinions of an author's work.
Literary critics analyze, describe, evaluate, interpret, or summarize a particular work and their comments can help you define your own views. Literary criticism also often discusses a work's historical context which may give you a better insight to an author's purpose. Many valuable pieces of literary criticism do not discuss specific titles in detail but rather evaluate a writer's work as a whole. Although such general discussions may not address your assigned short story or poem, they often provide information that can help you understand and interpret the work. Generally you will find indexes, bibliographies, etc., which usually point you to a complete article or book on criticism.