HTTP status codes are a response to a request for a webpage. Every time you type in a URL, click a link or get a search result, you are essentially requesting a document or web page from a server. HTTP status codes are 3-digit codes (like 200 OK, or 404 Not Found) sent from a web server to let people and search engines know if there were any mistakes in the request or any problems with the server trying to process the request.

HTTP status codes are important to diagnosing website issues, like if a web server is not working and not serving pages or if improper links have been created on a website that doesn't work. Catching all these issues quickly is really important to provide a good experience for people and search engines. If you want to rank well in search engines, you need to make sure your website is always working properly by reviewing status codes reported by the server.