Images can also act as hyperlinks just as normal text. Just as text is made as a hotspot so as an image. i.e, by enclosing the <img> tag wtihin the <a> ... </a> tags.
<a href="targetpg.htm"><img src="target.gif"></a>
Here the image acts as a hotspot and navigates to the file targetpg.htm
Just as an underline appears on the text if we enclose text within <a> ... </a> tags, a border will appear for the image that has been placed with in <a> ... </a> tags. You can remove the border by setting the border attribute of <img> tag to 0.