A type of continuous distribution, which describes or approximates a wide range of natural processes. E.g. when measuring the speed of vehicles at a given spot, or the size of carrots, the results will approximate a normal distribution.

The distribution is defined by two parameters; the mean, which controls the curve's placement, and the standard deviation, which controls the shape of the curve. When the mean equals zero and the standard deviation equals one, the resulting distribution is called the standard normal. The graphical representation of the normal distribution is also known as the bell curve.