# How to Tell a *Z*-Distribution from a *t*-Distribution

Although the normal (*Z*-) distribution and *t*-distribution are similar, they look different from each other and are used for different statistical purposes. The normal distribution is that well-known bell-shaped distribution whose mean is

and whose standard deviation is

The standard normal (or *Z-*distribution), is the most common normal distribution, with a mean of 0 and standard deviation of 1. The *t-*distribution can be thought of as a cousin of the standard normal distribution — it looks similar in that it’s centered at zero and has a basic bell-shape, but it’s shorter and flatter around the center than the *Z-*distribution. Its standard deviation is proportionally larger compared to the *Z,* which is why you see the fatter tails on each side.