Programmers' Day (Russian: День программи́ста) is an international professional holiday, recognized in many technology companies and programming firms, that is celebrated on the 256th (0x100th) day of each year (September 13 during common years and on September 12 in leap years). It is also officially recognized in Russia[1][2] and observed in several other countries including the United States, United Kingdom, Germany, France, China and Croatia.[citation needed]