This document provides an outline and introduction to information retrieval techniques. It discusses term-document incidence matrices as an initial approach, but notes their limitations with large collections. It then introduces the inverted index as a more scalable solution, where each term has a postings list of documents that contain it. The document explains how Boolean queries are processed by merging these postings lists. It also discusses phrase queries and how positional indexes store term positions to enable phrase matching. The document concludes by discussing combination indexing schemes that employ both biword indexes and positional indexes.