This book provides an overview of the important issues in information retrieval, and how those issues affect the design and implementation of search engines. Not every topic is covered at the same level of detail. The focus is on some of the most important alternatives to implementing search engine components and the information retrieval models underlying them. The target audience for the book is advanced undergraduates in computer science, although it is also a useful introduction for graduate students.

This version of the book is being made available for free download. It has been edited to correct the minor errors noted in the 5 years since the book's publication. The authors, meanwhile, are working on a second edition.