This document provides an introduction to software engineering and defines different types of software. It explains that software is a set of instructions that resides in the computer's memory or storage. There are two main types of software: system software, which operates and controls the computer hardware, and application software, which is designed for specific applications. Some common system software includes operating systems, databases, and programming tools. Examples of application software are word processors, spreadsheets, accounting programs, and web-based software.