Johann Carl Friedrich Gauss (1777-1855)  seen here on a German 10 Deutsche Mark banknote was a mathematician, astronomer, scientist noted for least squares, the normal distribution, and number theory.  Also known as the Gaussian distribution, the normal distribution is defined by the mean ("average", μ) and variance (standard deviation squared, σ2). The standard normal distribution is the normal distribution with a mean of zero and a variance of one.  Common applications include process modeling, queuing theory, safety stock and service level calculations, as was as statistical process control.