Nano (symbol n) is a unit prefix meaning "one billionth". Used primarily with the metric system, this prefix denotes a factor of 10^{−9} or 0.000000001. It is frequently encountered in science and electronics for prefixing units of time and length.
The prefix derives from the Greek νᾶνος (Latin nanus), meaning "dwarf". The General Conference on Weights and Measures (CGPM) officially endorsed the usage of nano as a standard prefix in 1960.
When used as a prefix for something other than a unit of measure (as for example in words like "nanoscience"), nano refers to nanotechnology, or means "on a scale of nanometres" (nanoscale).
Prefix  Base 10  Decimal  Adoption ^{[nb 1]}  

Name  Symbol  
quetta  Q  10^{30}  1000000000000000000000000000000  2022^{[2]} 
ronna  R  10^{27}  1000000000000000000000000000  2022 
yotta  Y  10^{24}  1000000000000000000000000  1991 
zetta  Z  10^{21}  1000000000000000000000  1991 
exa  E  10^{18}  1000000000000000000  1975 
peta  P  10^{15}  1000000000000000  1975 
tera  T  10^{12}  1000000000000  1960 
giga  G  10^{9}  1000000000  1960 
mega  M  10^{6}  1000000  1873 
kilo  k  10^{3}  1000  1795 
hecto  h  10^{2}  100  1795 
deca  da  10^{1}  10  1795 
10^{0}  1  —  
deci  d  10^{−1}  0.1  1795 
centi  c  10^{−2}  0.01  1795 
milli  m  10^{−3}  0.001  1795 
micro  μ  10^{−6}  0.000001  1873 
nano  n  10^{−9}  0.000000001  1960 
pico  p  10^{−12}  0.000000000001  1960 
femto  f  10^{−15}  0.000000000000001  1964 
atto  a  10^{−18}  0.000000000000000001  1964 
zepto  z  10^{−21}  0.000000000000000000001  1991 
yocto  y  10^{−24}  0.000000000000000000000001  1991 
ronto  r  10^{−27}  0.000000000000000000000000001  2022 
quecto  q  10^{−30}  0.000000000000000000000000000001  2022 

A nanosecond (ns) is a unit of time in the International System of Units (SI) equal to one billionth of a second, that is, 1⁄1 000 000 000 of a second, or 10^{−9} seconds.
The term combines the SI prefix nano indicating a 1 billionth submultiple of an SI unit (e.g. nanogram, nanometre, etc.) and second, the primary unit of time in the SI.
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.