\begin{definition}[Definition:Real Interval/Endpoints]
Let:
:$\closedint a b$
or
:$\hointr a b$
or
:$\hointl a b$
or
:$\openint a b$
be a real interval.
The numbers $a, b \in \R$ are known as the '''endpoints''' of the interval.
$a$ is sometimes called the '''left hand endpoint''' and $b$ the '''right hand endpoint''' of the interval.
\end{definition}