SEO, or Search Engine Optimisation, is the process of improving the visibility and ranking of a website or web page in search engine results pages (SERPs). It is done through optimizing the website content, structure, and on-page elements like titles, metatags, and anchor text, as well as developing off-page SEO tactics like link building and social media engagement. The goal of SEO is to increase the quantity and quality of traffic to a site from organic search results.