This document provides an overview of search engines and search engine optimization (SEO). It defines search engines as internet tools that search an index of documents for user-specified terms and return relevant results. Popular search engines like Google, Yahoo, and MSN are described. The document outlines why SEO is important for driving traffic and sales. Key aspects of SEO like algorithms, ranking factors, on-page and off-page optimization techniques are summarized. Basic tips are provided such as targeting keywords, obtaining inbound links, and monitoring rankings and traffic.