Imagine you are moving from an apartment to a house. You never forwarded your mail, so the bills begin piling up at your door and are returned to sender. Friends don’t know where to send the holiday cards.
A 404 error is the same concept when you relocate your website from one URL to another. A 404 status code tells the user that the page doesn’t exist or wasn’t found at this location.
Pages with 404 errors can lead to frustration for users, plus a drop in SEO rankings since search engines will simply not index a page that returns a 404 error.
The server itself will provide a standard page that isn’t very user friendly. Most businesses choose to customize a 404 page that includes a call to action (CTA) to let users know what to do next.