When you post a link in Facebook, FB looks for three elements for the display of the link. Title, description and an image.
The title comes from the <title>This is my Link</title> tag.
The description similarly comes from the META tag <meta name=”description” content=”The Description” />
The image basically looks at all the images on the page over 100 px, and then sorts it by the largest image first, and then position. The image can also have a style display of none so that it is hidden from the browser, but visible to FB.
