An operating system (OS) is the fundamental software that manages computer hardware and provides common services for running applications. Major operating systems include Microsoft Windows, Apple macOS, Linux, and mobile systems like iOS and Android. The operating system handles tasks like managing memory, processing input, displaying output, and running programs. Municipal IT decisions include which operating systems to support for staff computers, public access terminals, and servers. Standardizing on particular operating systems simplifies support and training. Security patches and updates for operating systems are crucial for protecting municipal networks and data from cyber threats.