Second (s)
Definition: The second (symbol: s) is the base unit of time in the International System of Units (SI). It is defined by taking the fixed numerical value of the caesium frequency ΔνCs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9,192,631,770 when expressed in the unit Hz, which is equal to s⁻¹.
History/origin: The second was originally defined as 1/86,400 of a mean solar day. In 1967, the second was redefined in terms of the caesium atom.
Current use: The second is used globally in science, engineering, and everyday life. It is the standard unit of time in most countries around the world.
Minute (min)
Definition: A minute (symbol: min) is a unit of time based on the second. It is equal to 60 seconds. Under Coordinated Universal Time, a minute can have a leap second, making the minute equal to 61 rather than 60 seconds.
History/origin: The minute was originally defined as 1/60 of an hour (60 seconds), based on the average period of Earth's rotation relative to the sun.
Current use: The minute is used globally for measuring durations, from cooking times to meeting schedules.