## RulesEdit

The `\rule`

command in normal use produces a simple black box:

```
\rule[depth]{width}{height}
``` |

The depth, width and height parameters are explained in the Boxes chapter.

Here is an example:

```
\rule{3mm}{.1pt}%
\rule[-1mm]{5mm}{1cm}%
\rule{3mm}{.1pt}%
\rule[1mm]{1cm}{5mm}%
\rule{3mm}{.1pt}
``` |

This is useful for drawing vertical and horizontal lines.

## StrutsEdit

A special case is a rule with no width but a certain height. In professional typesetting, this is called a *strut*. It is used to guarantee that an element on a page has a certain minimal height. You could use it in a tabular environment or in boxes to make sure a row has a certain minimum height.

In LaTeX a strut is defined as

```
\rule[-.3\baselineskip]{0pt}{\baselineskip}
``` |

## Stretched rulesEdit

LaTeX provides the `\hrulefill`

command, which work like a stretched horizontal space. See the Lengths chapter.