On-page SEO involves optimizing individual web pages by editing HTML and page content according to search engine rules. This includes optimizing page titles, meta descriptions, keywords, internal and external links, anchor text, and URLs. Off-page SEO refers to actions taken outside the website like link building, social media marketing, and social bookmarking to boost rankings. Effective off-page SEO methods include link building to gather external votes and boost rankings, as well as social media marketing to leverage social mentions as ranking factors.