The <line>
element, as the name implies does just that. It lets you draw lines. It takes attributes the specify the start and endpoint.
It takes the following attributes:
<svg xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink">
<line x1="10" x2="50" y1="110" y2="150"/>
</svg>