A second (s) is the base unit of time in the International System of Units (SI). It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom. This precise definition allows for accurate timekeeping and synchronization across various scientific and everyday applications. Seconds are commonly used to measure time intervals, such as the duration of events or the time taken to complete tasks. Clocks and watches typically display time in hours, minutes, and seconds, making it easy for people to understand and manage their daily schedules.