I was reading an essay on Paul Graham's blog[1] and the side panel[2] seemed erringly pixelated even on my MBP. I inspected the web page and found that the whole side panel is infact a gif[3] and the different links on the page are linked using the coordinates of the image.<p>Example for the first link:
<area shape="rect" coords="0,0,67,21" href="index.html"><p>TBH, I did not know this is something which can be done in HTML but that got me curious on how it ended up on PG's blog given many limitations it has :)<p>[1]: http://paulgraham.com/
[2]: https://i.imgur.com/uo254ts.png
[3]: https://s.yimg.com/aah/paulgraham/quotes-1.gif
It's just old; back in the day HTML had very little graphic capabilities, and loading multiple images was comparatively slow (think 56k connections). So you'd load a single image and then subdivide that in clickable areas with image maps (which is what this is called).
As other commenters have said, this used to be a very common technique.<p><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/map" rel="nofollow">https://developer.mozilla.org/en-US/docs/Web/HTML/Element/ma...</a>