Digital product design, workflow & collaboration
To put it bluntly, InVision is the Google Docs of Product Design. InVision makes it possible to create rich prototypes and product designs, then share them with the rest of the team.
On top of that, InVision features asynchronous feedback loops (not unlike Google Docs 'Suggest' function), a digital whiteboard (to easily suggest changes and ideas) and great handoff and presentation tools.
While not specifically mentioned, InVision seems to be built with remote teams in mind, putting a lot of effort into async collaboration.