The document outlines the history of computer viruses, types of viruses including boot sector, file, and program viruses. It discusses sources of virus attacks from downloadable programs, cracked software, email attachments, and booting from CDs. It covers prevention methods like not sharing drives, using antivirus software, and deleting suspicious email attachments. The document also examines antivirus software like Norton, McAfee, and Kaspersky that use signature-based, heuristics-based, behavioral, and cloud-based detection methods.