It is used to work with robots. The robots or EA only work when your platform is running and it will stop working when your platform is off. So this service keep your platform on when it is not working on your computer. You will have to pay to get this service. If you have less capital then don't go to use it because it will be difficult to manage expenses of VPS. Forex trader need VPS to run their robot. I ever have VPS and used it for robot. I traded using robot, and use VPS to keep it online for 24 hours per day. VPS is very cheap, then forex trader can use it to trade using robot than keep their pc online 24 hours per day