Containerizing services
The traditional way of operating services is to use a server using a full OS, such as Linux, and then install on it all the required packages (for example, Python or PHP) and services (for example, nginx, uWSGI). The server acts as the unit, so each physical machine needs to be independently maintained and managed. It also may not be optimal from the point of view of hardware utilization.
This can be improved by replacing the physical server with virtual machines, so a single physical server can handle multiple VMs. This helps with hardware utilization and flexibility, but still requires each server to be managed as an independent physical machine.
Multiple tools help with this management, for example, configuration management tools such as Chef or Puppet. They can manage multiple servers and guarantee that they have installed the proper versions and are running the proper services.