This textbook introduces the fundamentals of cybersecurity, covering the protection of computers, networks, and data from threats like viruses, malware, and phishing. It explains key principles such as confidentiality, integrity, and availability of data while highlighting cybersecurity's evolution from basic security measures to AI-driven protection. The book emphasizes its importance in critical sectors like healthcare and finance, differentiates cybersecurity from information security, and discusses common threats like ransomware. It also provides essential preventive measures, including strong passwords, software updates, and firewalls. Designed for beginner engineering students, this textbook offers a foundational understanding of cybersecurity and its evolving challenges.