A distribution is skewed if one of its tails is longer than the other.
The first distribution shown has a positive skew. This means that it has
a long tail in the positive direction. The distribution below it has a
negative skew since it has a long tail in the negative direction. Finally,
the third distribution is symmetric and has no skew. Distributions with
positive skew are sometimes called "skewed to the right" whereas
distributions with negative skew are called "skewed to the left."