Since you ONLY supplied a filename, the browser looks to load Paper.gif
from the same directory which the file is served from. It's commonly referred to as a "relative path."
For example, if you load http://example.com/index.html and that page references a background-image: url(background.png)
, it will look for http://example.com/background.png to load.
This is, of course, assuming you're not using an external stylesheet. If so, your relative path will load from the place that the stylesheet is served from. For example, if you load http://example.com/index.html, which references http://example2.com/style.css for its styling, and that stylesheet references a file named background.png
, the browser will look for a file at http://example2.com/background.png