Sampling (and sampling interval)

Recording a continuous signal's value only at evenly spaced instants, $\Delta t$ apart.

Sampling a continuous signal $f(t)$ at rate $f_s$ means recording the sequence $x_n = f(n\,\Delta t)$ , where $\Delta t = 1/f_s$ is the sampling interval, the fixed time gap between consecutive readings. Everything about $f$ between sample instants is permanently discarded.

Examples

A CD samples audio at $f_s=44{,}100$ Hz, so its sampling interval is about $22.7$ microseconds.