1) In general, the period of time that one component in a system is
spinning its wheels waiting for another component. Latency,
therefore, is wasted time. For example, in accessing data on a disk,
latency is defined as the time it takes to position the proper sector
under the read/write head.
(2) In networking,
the amount of time it takes a packet
to travel from source to destination. Together, latency and bandwidth
define the speed and capacity of a network.