If a visitor shares a link from your website on Facebook you're helpless to the thumbnail that Facebook decides to use. This can be a tad bit frustrating.

Here's a quick tip to specify the image Facebook will use. You will need to add the following tag to the head of your webpage:

link rel="image_src" href="http://www.example.com/images/image.jpg"

Please note that you will need to add this tag to any page that you would like to have control over the thumbnail image.