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This article is about the unit of time. See second (disambiguation) for other uses 
The second (symbol s) is a unit for time, and one of seven SI base units. It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom at zero kelvins.

In common reckoning of time, a second is 1/60 of a minute, and 1/3600 of an hour.

