404 is an HTTP status code. When you visit a web page, your computer is requesting data from a server using Hypertext Transfer Protocol (HTTP).

Before the web page is displayed, your browser sends the web server its HTTP header. The server responds with its HTTP header, which contains the status code.

For a normal web page, the status is 200 (OK). You don't see this because the server just sends you the content of the page.

If you encounter an error, then you see the actual status code, such as 404 Not Found.

The first 4 indicates a client error. The server is saying that you've done something wrong, such as misspell the URL or request a page which is no longer there. (For comparison, a 5xx error indicates a server-side problem, which may be transient; if you try it again, it may work.)

The middle 0 refers to a general syntax error. This could indicate a spelling mistake.

The last 4 just indicates the specific error in the 40x group, which also includes 400: Bad Request, 401: Unauthorized, etc.
404 not found
by johnhms July 12, 2008
Top Definition
Error returned when a server cannot find the requested page.
Once upon a midnight dreary, while I websurfed, weak and weary,

Over many a strange and spurious website of 'hot chicks galore',

While I clicked my fav'rite bookmark, suddenly there came a warning,

And my heart was filled with mourning, mourning for my dear amour.

"'Tis not possible," I muttered, "give me back my cheap hardcore!"

Quoth the server, "404".
by mikm May 30, 2005
Sorry, this definition could not be found.
What's up with this new character limit thing, anyway? It pisses me off.
by wysiwyg August 12, 2004
You are seeing this definition because Urban Dictionary thought it would be a good idea to make this their 404 page!
I got the 404 error also!
by 403 - Forbidden February 18, 2005
Someone who's clueless. From the World Wide Web error message "404 Not Found," meaning that the requested document could not be located.
"Don't bother asking him... he's 404, man."
by Zak May 03, 2003
Area code for those inside the Atlanta city limits; Person living "inside the perimeter," as it were, as opposed to 770, the metro area code, for the suburbs... Also a term of pride tossed about casually when representin' the ATL.
Is she 404 or 770?
404, A-Town all da way.
by Patience Ann February 04, 2003
webpage not at this address.
From internet error 404 - File Not Found
You step in the stream,
But the water has moved on.
This page is not here.
by mandingoe April 29, 2004
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