This document provides an introduction to computers, including definitions and characteristics. It defines a computer as a device that performs calculations at enormous speed and operates on data. The main characteristics of a computer are described as speed, accuracy, large memory, programmed intelligence, diligence, versatility, and powerful remembrance. The document also discusses different types of computers such as analog, digital, and hybrid computers. Computers are classified by size and power as personal computers, workstations, mini computers, mainframe computers, and super computers. The advantages of computers include speed, powerful search engines, calculating power, storage, and communication capabilities. The disadvantages are potential health risks, privacy violations, public safety issues, inability to think for itself, and