What does YYYY stand for?

What does YYYY mean?

YYYY	Four-digit Year Business » General
YYYY	Four-digit year date Governmental » NASA
YYYY	Four-digit year date Governmental » Military
YYYY	Four-digit year date Academic & Science » Meteorology
YYYY	Four-digit year date Academic & Science » Ocean Science
YYYY	Four-digit year date Academic & Science » Universities
YYYY	Four-digit year date Business » International Business
YYYY	Four-digit year date Computing » Software
YYYY	Four-digit year date Governmental » Transportation
YYYY	Four-digit year date Governmental » United Nations
YYYY	Four-digit year date Medical » Laboratory
YYYY	Four-digit year date Governmental » US Government