The t-distribution, also known as the Student’s t-distribution, is a statistical function that creates a probability distribution. The t-distribution is similar to the normal distribution, with its bell shape, but it has heavier tails. It is used for estimating population parameters for small sample sizes or unknown variances. T-distributions have a greater chance for extreme values than normal distributions, and as a result have fatter tails.

The t-distribution is the basis for computing t-tests in statistics.