SEO involves optimizing websites to rank higher in search engine results. Key on-site factors include using search engine friendly URLs, 301 redirects, optimized title and meta tags, avoiding keyword stuffing, creating an XML sitemap, using a robots.txt file, proper use of HTML headings and tags, alt text for images, text links with title attributes, and managing 404 error pages. Off-site factors involve link building, social media relevance, and selecting keywords based on goals and audience. The document provides guidelines and best practices for implementing various on-site SEO techniques.