The Olympic Games are competitions in different sports that originated in Ancient Greece and was revived in the late 19th century. They are held every four years.
In 1924, the Winter Games were sanctioned for winter sports. Originally, this occurred on the same years as the Summer Games, but they were held in 1992 and again in 1994 and thereafter every four years; the Summer Games maintain their original four-year cycle.
Before the 1970s the Games were officially limited to competitors with amateur status, but in the 1980s many events were opened to professional athletes.