A nanosecond (ns) is an SI unit of time equal to one thousand-millionth of a second (or one billionth of a second), that is, 1/1,000,000,000 of a second, or 10−9 seconds.
The term combines the prefix nano- with the basic unit for one-sixtieth of a minute.
A nanosecond is equal to 1000 picoseconds or 1⁄1000 microsecond. Time units ranging between 10−8 and 10−7 seconds are typically expressed as tens or hundreds of nanoseconds.
Time units of this granularity are commonly found in telecommunications, pulsed lasers, and related aspects of electronics.