# Definition:Real Interval/Length

## Definition

Let:

$\left[{a \,.\,.\, b}\right]$

or

$\left[{a \,.\,.\, b}\right)$

or

$\left({a \,.\,.\, b}\right]$

or

$\left({a \,.\,.\, b}\right)$

be a real interval.

The difference $b - a$ between the endpoints is called the length of the interval.