Often an experiment yields a result that can be classified according to a set of discrete events, giving rise to an integer count or set of integer counts as a result. For example the measurement of a radioactive decay may yield the number of counts in a detector over a period of time. The measurement of the scattering of a beam of particles from a target may yield so may counts over a particular range of deflection angles over a period of time. Any series of measurements, the result of which can be classified into histogram bins, produces counts. In this section we will discuss briefly the statistics of counting, with particular emphasis on Poisson statistics.