Cyber crime involves illegal activities conducted through computers and networks. It is categorized as crimes against persons, property, or government. Common types of cyber crimes include botnets, ransomware, and identity theft. Botnets are networks of compromised computers controlled to perform malicious tasks. Ransomware encrypts files and demands payment for access. Identity theft involves stealing personal information to commit fraud. Prevention methods include keeping systems updated, using strong passwords, protecting personal information, and using security software like firewalls and antiviruses.