This document outlines the main factors that Google uses to rank websites, including: 1. On-page factors like keywords in titles, content length, and image optimization. 2. Off-page factors like backlinks, social signals, and the authority of linking pages. 3. Site-wide factors like site architecture, contact pages, and frequency of updates. It provides examples and brief explanations for some of the most important ranking factors at the domain, page, site, backlink, social, and technical levels.