This document discusses different types of query languages used for information retrieval systems. It describes keyword queries where documents are retrieved based on the presence of query words. Phrase queries search for an exact sequence of words. Boolean queries use logical operators like AND, OR and NOT to combine search terms. Natural language queries allow users to enter searches in a free-form manner but require translation to a formal query language. The document provides examples and explanations of each query language type over its 12 sections.