This document discusses the classification of operating systems presented by Dr. Pankaj Kumar. It describes batch operating systems, interactive operating systems, time-shared operating systems, distributed operating systems, network operating systems, real-time operating systems, embedded operating systems, and mobile operating systems. For each type of operating system, it provides examples, advantages, and disadvantages. The document aims to outline the different types of operating systems for B.Tech second year students taking the Operating System course (KCS-401) taught by Dr. Pankaj Kumar.