This document discusses the evolution of server technologies from mainframes to modern containers and Platform as a Service (PaaS). It outlines the abstraction layers from bare metal infrastructure to PaaS. Key technologies at each layer like virtual machines, containers, Docker, Kubernetes, and PaaS platforms are presented. The advantages and disadvantages of different approaches are compared. Emerging trends toward ephemeral runtimes, portability across clouds, and hybrid setups are also noted.