A light-year is a unit of astronomical distance, defined as the distance light travels in one year. A parsec is another unit of astronomical distance, approximately equal to 3.26 light-years. A furlong is a historical unit of distance, typically equal to one-eighth of a mile (201.168 meters). A jiffy is colloquially used to mean a very short period of time. In some technical contexts (e.g., computing, physics), it can be a defined unit of time, typically very short (e.g., the duration of one cycle of the AC power line).