The document defines SEO as optimizing a website for search engines through techniques like keyword research, on-page elements like meta tags and content, and off-page elements like linking and social signals. It discusses major search engines, how they work by crawling, indexing and ranking pages, and types of SEO like white hat, black hat and gray hat techniques. On-page optimization involves keywords, meta descriptions, images, internal links and content optimization, while off-page focuses on link building through articles, directories and social media.