Popcorn Time is an open source media player. That means developers can copy the source code of its software and make it available on another website. Each new version of the software is called a "fork." When new forks are created, this creates a "Whac-A-Mole" effect for governmental agencies trying to stop the spread of piracy -- as soon as a fork gets shut down, another one pops up. A visual of the fork process is available below:
If you're a Netflix investor, there's no need to panic. Popcorn Time is spreading rapidly, but there's no proof that it has affected Netflix's operations thus far. But it might be a good idea to keep an eye out for slowing international subscriber growth over the next few years as it could be the result of developments in piracy applications.