An SEO checker is a tool that analyzes a website's search engine optimization (SEO) and provides recommendations for improving its ranking in search engine results pages (SERPs). SEO checkers can be used to assess a variety of factors that impact the visibility and ranking of a website in search engines, such as the quality and relevance of the website's content, the structure and organization of the website, and the presence of keywords and other elements that help search engines understand the website's content. Some SEO checkers also provide recommendations for optimizing the website's technical aspects, such as the loading speed and mobile-friendliness of the website. By analyzing these and other factors, an SEO checker can help website owners and marketers identify and fix problems that may be preventing their website from ranking well in search engine results.