The continuous probability distribution with probability density function f given by f(x)=λ exp(−λ x), where λ is a positive parameter, and x≥0. It has mean 1/λ and variance 1/λ2. The time between events that occur randomly but at a constant rate has an exponential distribution. The distribution is skewed to the right. The following figure shows the probability density function of the exponential distribution with λ=10.