This Image is Also an HTML Webpage

Here is an image:

But it is also an HTML page. Here is the markup for the above image:

<img src="http://lcamtuf.coredump.cx/squirrel/" />

Now try visiting that webpage:

Pretty cool, eh?

I did not make this. I am just showing you because it is cool.

Here is an explanation of what is happening:

The file is a valid jpeg file with some html in metadata.
The server responds with Content-Type: text/html, making browser interpret the response body as html.
Browser ignores jpeg header until it sees and starts to render the html.
The html in the jpeg metadata ends with "<!--" , which starts html comment.
The html has that renders the file as image.