This document provides an introduction to search engine optimization (SEO). It defines SEM as search engine marketing using both organic and paid search. Organic search relies on search engine optimization to gain prominence in unpaid search results, while paid search uses advertising to control sponsored links. The document outlines various on-page and off-page optimization techniques for SEO, including optimizing content, metadata, site structure, URLs, and images. It also discusses the importance of linking strategies like building high-quality backlinks. Regular evaluation and improvement is emphasized for an effective long-term SEO strategy.