A discrete signal or discrete-time signal is a time series consisting of a sequence of quantities.
Discrete signal is a type series that is a function over a domain of discrete integral.
Unlike a continuous-time signal, a discrete-time signal is a function of a continuous argument. However, it may have been obtained by sampling a continuous-time signal, and then each value in the sequence is called a sample. When a discrete-time signal obtained by sampling is a sequence corresponding to uniformly spaced times, it has an associated sampling rate; the sampling rate is not apparent in the data sequence, and so needs to be associated as a separate data item.
Source: Wikipedia.
