Koninginnedag or King’s Day is a national holiday in the Kingdom of the Netherlands. Celebrated on 27 April (the 26th if the 27th falls on a Sunday), the date marks the birth of King Willem-Alexander. Koningsdag is known for its nationwide vrijmarkt (« free market »), at which many Dutch sell their secondhand items. It is also an opportunity for « orange madness » or oranjegekte, for the national colour, when the normally strait-laced Dutch let down their hair, often dyed orange for the occasion.