Search engine optimization (SEO) is the process of optimizing a website or web page to increase its visibility and rank higher in search engine results pages (SERPs). The goal of SEO is to make it easier for search engines to understand the content on a web page and to make it more relevant and useful to users who are searching for information related to the content on the page. This is typically achieved by optimizing the website's content, structure, and HTML code, as well as by building high-quality links from other websites to the target site.