Search Engine Optimization (SEO) refers to the process of optimizing a website to improve its visibility and ranking on search engine results pages (SERPs). SEO involves a combination of techniques, including keyword research, content optimization, and link building, to help websites attract organic traffic from search engines like Google, Bing, and Yahoo. SEO is divided into two main categories: on-page SEO, which focuses on optimizing content and structure within a website, and off-page SEO, which involves external factors like backlinks. A well-executed SEO strategy helps businesses increase their online presence, attract relevant visitors, and improve conversions.