The document discusses different types of computer viruses including worms, time bombs, logic bombs, boot sector viruses, DOS viruses, Trojans, and how antivirus software works to detect and remove viruses. It provides examples of some common computer viruses throughout history for each type and explains how they work, such as by modifying the boot sector, setting time triggers, or disguising as legitimate files to gain access and run malicious code on an infected system. Prevention methods like keeping antivirus software up to date, not opening suspicious emails, and backing up files are recommended to avoid virus infections.