Typically, the PostgreSQL server will start automatically when the system boots. You may have opted to stop and start the server manually, or you may need to start up or shut down for various operational reasons.
First, you need to understand the difference between the service and the server. The word "server" refers to the database server and its processes. The word "service" refers to the operating system wrapper by which the server gets called. The server works in essentially the same way on every platform, whereas each operating system and distribution has its own concept of a service.
On all platforms, there is a specific command to start the server: