SEO is the process of optimizing a website to increase its visibility in organic search engine results. It involves implementing on-page techniques like optimizing titles, meta descriptions and headings, as well as off-page techniques like link building. The goal is to meet search engine guidelines and provide beneficial information to users in order to rank highly and drive more traffic to the site. Both white hat and black hat techniques exist, with white hat being search engine friendly approaches like content creation, linking, and social sharing.