Cyber crime involves unlawful acts where a computer is used either as a tool or target. The document discusses the history of cyber crimes from the first recorded incident in 1820. It categorizes cyber crimes as those targeting computers or using computers as weapons to commit real-world crimes. Various types of cyber crimes are explained such as hacking, DDoS attacks, viruses, phishing, and cyber terrorism. The document emphasizes that cyber crimes threaten national security and discusses cyber security and Indian cyber laws.