So what does 404 actually mean? The first ‘4’ means you’ve done something wrong, either misspelling the URL or requesting a page that’s no longer there.

The middle ‘0’ simply refers to a general syntax error, meaning the URL is misspelled.

The last ‘4’ refers to the specific error in the group of 40x.

Why is it called error 404? In the past, it was speculated that error 404 was named after a room at CERN (European Organization of Nuclear Research) where the original web servers were located. However, this speculation was disproved by Tom S., who said that he couldn’t find Room 404 when he visited.

He proceeded to explain the CERN office numbering system where the first digit ‘4’ refers to the building number while the last 2 digits the office number.

“Sorry to disappoint you all, but there is no Room 404 in CERN – it simply doesn’t exist, and certainly hasn’t been preserved as “the place where the web began”. The whole “Room 404” thing is just a myth.”

The theory: Error 404 might just be based on Room 404 in CERN, simply because both can’t be found in this world. Someone in the past might have went, hey there’s no room 404 here, let’s use that as a code for something that doesn’t exist, shall we?