Image hotlinking is a way most spammers display images to their blog using your own bandwidth. This in turn hogs your bandwidth; therefore causing you to pay more than what you need or getting your site exceed bandwidth limit for no reason. To fight against image hotlinking, we enter a command in the .htaccess file but as a result, it will also prevent your images to appear in the feeds. Although this can be solved, writing htaccess codes can be a bit intimidating specially for novice users.
Here is a plugin which lets you save from doing all the work. It prevents image hotlinking by simply installing and activating this plugin.
Read the rest of the post here: http://www.hongkiat.com/blog/protect-wordpress-blog-against-image-theft-hotlinking/