What is a 404 'not found' message?

A 404 not found message is shown when a user clicks on a link that doesn't exist, has been disabled, or has been deleted.

It comprises two parts:

• A visible part that a user sees - a message that lets the user know that this URL doesn't exist.
• An invisible part - a machine readable error code that's part of the HTTP specification, designed to let computers understand this page doesn't exist. Different types of errors have numbers, and this one is designated 404.

What will a user see when a link is 'not found'?

A user will see a message that looks like this: