We may think, that counter shown near the Facebook share button at some blog post represents the count of unique Facebook users who have actually shared the link to that post on their wall. Similarly, we think that the counter near the Like button represents the count of unique Facebook users who have liked that post(link). But that is not true, the stats do not exactly represent what we may generally perceive them to be.
I became suspicious about the facebook share button count, when the count on one of my blog posts, had reached 6 yesterday. For a moment, I was pleasantly surprised that my post was getting shared across the web by a few facebook users. But after a moment, I realized that there was something wrong, because firstly, the post was not something great and secondly, I do not have a large (or actually even small) fan following that my post would be shared 6 times within a day. Investigating the reason behind it on the web, I discovered what that count actually represents.
Facebook share count = No. of times it has been shared + No. of comments on that shared wall post + No. of likes on that shared wall post.
At the time of writing this blog, the Facebook share count on that post was 7, which was because I had shared this link on my profile page and on my facebook page for this blog, and 4 comments were made on that shared post at my profile page and 1 like for that post at my profile page.
So, the question is how can we actually get to know the number of unique users who actually shared a blog post or link. To get the exact count, you can copy paste the line below into your browser's address bar, replacing the URL_YOUR_LINK by url of the blog post or any other link that has been shared on facebook.
<share_count> tag value represents actually how many times your link has been uniquely shared by distinct facebook users. But the count we see near the facebook share button is value of <total_count>.
For example, for viewing the actual stats of my blog post, click on this link or copy this link http://api.facebook.com/restserver.php?method=links.getStats&urls=http://technoflirt.com/noflirt/2010/12/12/sticky-note-part-2/ into your browser's address bar.
Similarly, the stats for Facebook like button counter is actually the value of <total_count> tag value. For example, the number of likes on Drupal: Facebook-style Micropublisher Preview is shown as 5, but if you click this link http://api.facebook.com/restserver.php?method=links.getStats&urls=http://publicmind.in/blog/fbsmp_preview/ , you will notice that <like_count> value is actually 4.
Thus, the bottom line is that facebook share counts and facebook like counts are actually deceiving. However, the comments or likes made by a facebook user xyz on a post abc shared by another facebook user abcd, are in some sense helping share the link as these activities appear in news feed of that user xyz as "user xyz likes some abc link" or "user xyz has commented on user abcd's link" . Such activities are now visible to the user xyz's connections. So, comments and likes are related to sharing a link. But even if the same user comments 5 times on a shared post, the facebook share button count increases by 5, because this count is related to how many times the link appears in the facebook activity feed of all the facebook users. So, I guess the count should actually represent the unique number of users who share, comment or like some link/post i.e. keep count of the unique association of users with some link.