Direct Linking:

Also see:
Definition of "Hotlinking"
  and
Free Hotlinking Checker - Test Your Hot Linking Protection

"Direct Linking" is a term referring to when a web page of one website owner is linking directly to the images or other multimedia files on the web host of another website owner (not just linking to a web page on their server which loads the image).  If this is done without permission, it is stealing bandwidth and is also known as "hotlinking", "hot linking", "leeching", and "bandwidth theft".  Here are a list of free image hosts which allow you to store images on their server at no cost (free) and allow you to direct link the hosted image files on forums (for avatars and signatures) or other websites.