what is a decade

A decade is a period of ten years. It can refer to any ten-year period, such as those of a persons life, or specific groupings of calendar years. The most widely used method for denominating decades is to group years based on their shared tens digit, from a year ending in a 0 to a year ending in a 9. For example, the period from 1960 to 1969 is the 1960s, and the period from 1970 to 1979 is the 1970s. Sometimes, only the tens part is mentioned, such as '60s or sixties, and '70s or seventies, although this may leave it ambiguous as to which century is meant. In common usage, a decade is a ten-year period beginning with a year ending in 0, such as 1980 to 1989.