This document provides an overview of information systems and their evolution. It begins by defining key terms like data, information, and information systems. It then describes how information systems have evolved over time, starting from the mainframe era where only large organizations could afford room-sized computers, to the PC revolution bringing computers to businesses and individuals with the launch of the IBM PC. The document traces this evolution through additional stages like client-server systems and the modern Internet-connected world. It provides examples and context throughout to illustrate how information systems have transformed and taken on new roles within organizations over decades of technological advancement.