Absolute 
  vs Relative URLs:
  
  Absolute URL:
  ex. http://www.mysite.com
Relative URL:
  ex. mypage.html/horse1.html
  
  An absolute URL points to a page on the Internet outside of where your site 
  lives. 
  A relative URL points to files relative in location to itself (in folders on 
  your site).
Use relative URL's when possible. Keeping all of your site assets in one place on the web for your site relative to eachother in one package. This way you can move your files and nothing will break.
sample site: