Latency

          Latency is the amount of time a message or data packets takes to traverse a system. You must have heard of Network Latency, so in computer networking it is an expression of how much time it takes for a data packet to get from one source system to destination another. It is more accurately measured as the time required for a packet to be returned to its sender over a interconnected network.

         

So if latency is low then network performance is good and on the other hand if latency is high then there supposed to be some problem with communication medium. In fact Latency depends on the speed of the transmission medium (e.g., copper wire, optical fiber or radio waves) and the delays in the transmission by devices along the way (e.g., routers and modems).

        Latency and throughput are the two very important terms to confuse about in data communication over the network. In fact both are fundamental measures of network performance with slightly different context. The latency measures the amount of time between the start of an action and its completion; throughput is the total number of such actions that occur in a given amount of time. Latency is measured in time (e. g. seconds,milliseconds) whereas throughput is measured in volume of data per unit time (e.g. gb/hr).