When viewing a page in a web browser, the web browser sends a request to the server where the page data is stored behind the scenes.

The server responds to the request and sends the data to the web browser, and the page is displayed in the web browser.

A 404 error is one of the responses sent by the server to a request made by a user searching or typing in a URL manually, and it means that the specified URL is a page that does not currently exist.