How does a VPN work?
Its simple. Your computer or phone connects to the VPN provider through an encrypted tunnel which is virtually impossible to hack or intercept. The second step is that the VPN provider forward all your data/information making it look like it is the VPN provider who is sending and receiving all the data. Anybody trying to trace your VPN provider's IP instead of yours. The encrypted communication between you and the VPN makes it very hard to trace you. It also provides you with extra security if you surf on an open WIFI since all the communication is completely encrypted between you and the outside world.
Platforms and Speed
The Platform and speed is probably where you will find the biggest differences between the various providers. While most providers do support Windows and OSX they still come with “if then else” options. Some requires you to login using specific software while others use more general solutions.
Most providers offers ability to download files using Torrents anonymously, but only a few gives you the ability to stream movies from Netflix.
The functionality and speed might vary, but it's usually not possible to motivate the big price difference between a $3/month and a $20/month VPN. This is also the reason for excluding
a couple of very costly VPNs that otherwise performed admirable. A special note; CyberGhost and NordVPN performed in top 5 in all tests while having among the most competitive / affordable prices.