In the weeks preceding Christmas or "jõulud", children place a slipper in their windows and receive a piece of candy or some other sweets from visiting elves ("päkapikud"). Estonians celebrate Christmas on December 24, which is referred to as "jõululaupäev" ("Christmas Saturday") and is by act of Parliament a public holiday in Estonia. Each year on this day, the President of Estonia declares the Christmas Peace and attends a Christmas service. The tradition was initiated by the order of Queen Christina of Sweden in the 17th century. Estonian children are visited by "jõuluvana" ("Santa Claus") on Christmas Eve, and must sing songs or recite Christmas poems before receiving their gifts.