Imagine, that you are working on a website project, and your developer sent you a mock up – a simple draft, uploaded on a temporary server so you can review it at once.
I used to work with clients who will print the mock up on paper, jotted his comments across the pages, scanned it all and sent it back to me. God help me if he is a doctor – it took a while for me to decipher each codes and symbols of the scribbles that my client try to tell me.
Thankfully, now we have Designcrit.io – where you can comments on any part of the pages, on the fly, and share it with your developers.