A picosecond is a unit of time equal to one trillionth of a second, or 10^-12 seconds. It is often used in fields like physics and chemistry to measure extremely fast processes, such as the movement of electrons or the duration of laser pulses. In practical terms, a picosecond is so brief that it is difficult to comprehend. For example, light travels about 0.3 millimeters in a picosecond, which is a tiny fraction of the distance it can cover in a second. This precision is crucial in technologies like fiber optics and high-speed photography.