What is faster than a zeptosecond?

What comes before a zeptosecond?

The only time units shorter than a zeptosecond are the yoctosecond and the Planck time. A yoctosecond (ys) represents a septillionth of a second. Now, how do we derive the Planck time? It involves a simple calculation: take the incredibly small Planck length and divide it by the speed of light, which is impressively large. This gives you a minuscule unit of time known as the Planck time!