Now let's use this image as a means of navigating - I will obviously use a small image for this...

To get rid of the border around the image, I can do the following:

The problem with this is that it only works well when using an arrow or something that makes it clear that this is for the user to press.
Note that src and alt are the only required tags for img and in fact it is better to size an image outside of your web page and load the correctly sized image rather than use width and height.