404
404 may refer to:

404 (number)
AD 404
404 BC
HTTP 404, the HTTP error response status for "Not Found"

Cars
Peugeot 404
Bristol 404, produced in the 1950s
Unimog 404

Highways
A404(M) motorway, in England
Ontario Highway 404, in Canada
Maryland Route 404, in the U.S.
List of highways numbered 404

Other uses
404 Error Not Found (film), a 2011 Hindi film
404 (band), a band signed to Dirty Hit
Project 404, a United States military mission to Laos during the Vietnam War
Alitalia Flight 404, an Alitalia-Linee Aeree Italiane flight that crashed on 14 November 1990 killing all on board
Martin 4-0-4, an American pressurized passenger airliner built by the Glenn L. Martin Company
Area code 404, a telephone area in Atlanta
Section 404 of the 2002 Sarbanes–Oxley Act
Room 404 – The Wrong Man, the second room in the 1995 film Four Rooms
"404", a song by Ram Jam from the 1977 album Ram Jam

See also
The 404 (disambiguation)