For students and researchers. If you're operating a business you still have to pay for VS licenses, or violate the free license and hope you get big enough fast enough that it's not a problem.
No I believe a company can use it up to 5 developpers. Which should cover the vast majority of start ups. Then you can buy a pro license for $500 which isn't that expensive if you have the financing for more than 5 devs.
