An "HTTP Error" occurs when a web server cannot fulfill a request made by a client, usually a web browser. These errors are indicated by specific status codes, such as 404 for "Not Found" or 500 for "Internal Server Error." Each code provides information about the nature of the problem, helping users and developers understand what went wrong. HTTP errors can arise from various issues, including broken links, server misconfigurations, or problems with the client's internet connection. When users encounter these errors, they may see a message on their screen, prompting them to check the URL or try again later.