These are status codes reported by the web server when accessing a certain web page:
401 - occurs if you try to access a website with incorrect information that requires a username and password for access
403 - occurs when the web server does not have the necessary permissions to serve web pages, the problem is most often caused by the error of the administator who edits the web pages
404 - occurs when you try to load a web page that does not exist, for example, maybe the requested object really does not exist, maybe the administator incorrectly "linked" the file on the web page, or maybe you just entered the wrong address in the browser
500 - occurs when an error occurs when executing a script or program on the web server, the problem is most often caused by the error of the administrator who edits the web pages