title: CSS Background URL
body: <p>Can someone help explain how exactly the CSS URL for a background image works? How exactly does the CSS know where to start looking up the URL? for example I have these 3 URLs</p>
  
  <pre><code>#web_content{ background: URL(images/background.jpg); }
  #web_content{ background: URL(/images/background.jpg); }
  #web_content{ background: URL(localhost:1234/newWebSite/images/background.jpg); }
  </code></pre>
  
  <p>I tried all 3 of these on different PCs. Using the same web browser that are the same versions and everything. Basically all that was different was the PC it ran on. Using the 1st example it showed only on one PC, the 2nd example showed on 2 PCs and the 3rd one showed on all of them... but of course in real life using that as the URL won't work. Can someone explain in detail how the URL finds the file?</p>