Suppose you just finished reading a hilarious comic strip online. To share this strip with your friends, you can deploy the URL of the comic on your social networking account. Adding any comments with the ‘share’ will only indicate what you felt about the strip as a whole. If you want to specify which part of the strip you liked you cannot do so without going into great details.
What we need is a commenting tool that lets us add comments to webpages themselves. Our comments can be placed right next to the webpage area the comment is referring to. That way our contacts can read a part of the webpage and find out immediately what we thought about it. It can also be a way to highlight the most funny / interesting part of a webpage which our contacts can skip to.