Exponential Distribution

In probability theory and statistics, the exponential distribution (a.k.a. negative exponential distribution) is theprobability distribution that describes the time between events in a Poisson process, i.e. a process in which events occur continuously and independently at a constant average rate. It is a particular case of gamma distribution. It is the continuous analogue of the geometric distribution, and it has the key property of being memoryless. In addition to being used for the analysis of Poisson processes, it is found in various other contexts.

Note that the exponential distribution is not the same as the class of exponential families of distributions, which is a large class of probability distributions that includes the exponential distribution as one of its members, but also includes thenormal distribution, binomial distribution, gamma distribution, Poisson, and many others.