This document provides an overview of accounting information systems. It defines key terms like transactions, information systems, accounting information systems, and subsystems. It describes how information flows within a business both horizontally and vertically. It also explains how data is collected and transformed into useful information for decision making through functions like data collection, processing, management and generation. The document outlines the evolution of information systems from manual to flat-file to database models. It discusses the roles of accountants as users, designers and auditors of information systems.