Invision is a great tool that allows you to not only provide your clients with a excellent prototype but has powerful features like live sharing, commenting, workflow tools, project management and mood boards. Perhaps you are developing an app first you want to see the icon on your home screen of your iPhone and swipe through the app see the animations, menus, links all in action. With invision you can do this easily giving your clients an app like feel before the app is even built. You might say why do this? The answer is simple once you actually flow through an app by clicking take a photo, next or accept you quickly realize the user experience and how there typically is elegance missing. Elegance in user experience is key to having happy users that enjoy your product that’s simple and intuitive.  From wireframing a software build, website or app Invision is key for developing these prototypes. Also during the design phase its important for everyone involved in the project to leave comments on certain areas of the design. With threaded comments, spot commenting it just so easy to understand and illustrate your views. Check it out here: http://www.invisionapp.com/