Granted, there are lots of applications that let you do something similar. But there is a key difference at play here, namely the many ways in which you can have screenshots annotated once they have been taken. Lots of edition tools are provided to these purposes.
You will be able to use figures like circles and rectangles, and you will also be able to draw as many lines and arrows as you need to be sure the message you want conveyed is really getting through. And you can capture both whole screens and just specific portions of pages, according to what you need to communicate.
Awesome Screenshot can be used for free. Just get the extension and install it. Both Chrome and Safari are already supported. And those who use Firefox should be catered for before too long.
AwesomeScreenshot.com In Their Own Words
Capture, Annotate and Share.
Why AwesomeScreenshot.com It Might Be A Killer
It is a great tool for collaboration – practical, fast and free. What more could you ask for?