The box created by \hphantom has the width of its argument, but its height and depth are zero (so it doesn't contribute to any vertical spacing issues). In other words, \hphantom creates horizontal space equal to that produced by its argument, but doesn't create any vertical space.

EXAMPLE

```
\begin{array}{l}
\text{Side Angle Side}\\
\text{S}\hphantom{\text{ide }}\text{A}\hphantom{\text{ngle }}\text{S}
\end{array}
```
$ \begin{array}{l} \text{Side Angle Side}\\ \text{S}\hphantom{\text{ide }}\text{A}\hphantom{\text{ngle }}\text{S} \end{array} $