The normal distribution is a continuous probability distribution with the following characteristics:

It is symmetric about the mean
The curve extends from minus to plus infinity
The limit of the total area under the curve is 1
The curve is always above the x-axis, that is f(x) is always positive (where x is a random variable and f(x) represents the density function)
The mean=mode=median A random variable that follows a normal distribution is called a normal random variable.

Standard normal distribution This is a typical normal distribution where the mean=0 and the variance=1.