Olympiad beginning on the opening of the Olympic Games for the summer sports. The first modern Olympiad began in 1896, the second in 1900, and so on (the 31st began in 2016: see the Olympic Charter). The ancient and modern Olympiads would have synchronised had there been a year zero between the Olympiad of 4 BC and the one of 4 AD. But as the Gregorian calendar goes directly from 1 BC to 1 AD, the ancient Olympic cycle now lags the modern cycle by one year. An ancient Olympiad was a period of four years grouped together, counting inclusively as
Olympiad "secret" and "spontaneous" events such as flash mobs. The English term is still often used popularly to indicate the games themselves, a usage that is uncommon in ancient Greek (as an Olympiad is most often the time period "between" and including sets of games). It is also used to indicate international competitions other than physical sports. This includes international science olympiads, such as the International Geography Olympiad, International Mathematical Olympiad and the International Linguistics Olympiad and their associated national qualifying tests (e.g., the United States of America Mathematical Olympiad or the North American Computational Linguistics Olympiad), and also events in