How Does This Work?

I hear a lot about Tumblr, but like many other things out here in La-La-Land nobody wants to talk about what Tumblr does that makes it worth talking about. Could it be it does not work, has not found a base of supporters to bring it to the surface of other reasons why you would want use it.

OR, it is a fabulous tool and one that needs to be added to bag of tools used to connect with people. Either way, the question still remains, how do you use Tumblr?