Introduction to IT Systems is a thoroughly designed, foundational textbook that provides learners with essential digital skills required in today technology-driven world. Covering everything from basic internet operations to advanced system management and cybersecurity, the book serves as a complete guide for students, educators, and professionals entering the field of information technology.The content begins with fundamental internet skillsbrowsers, search engines, portals, digital literacy, and the Digital India ecosystemempowering learners to navigate the online world confidently. The second section introduces core computer concepts, including hardware components, software types, data handling, networking essentials, and emerging technologies such as AI, machine learning, cloud computing, and virtual/augmented reality.A dedicated unit on operating systems provides hands-on knowledge of Windows and Linux installation, dual booting, troubleshooting, security settings, and post-installation configuration. Learners also acquire practical experience with Unix shell navigation, commands, vi editor, scripting, and environment variables.The book further equips readers with modern web development skills through HTML and CSS, enabling them to create, style, and publish functional personal webpages. The final unit focuses on comprehensive information security best practicescovering cyber threats, encryption, risk management, secure coding, network security, incident response, and regulatory compliance.With real-world examples, step-by-step tutorials, glossaries, and exercises, this book is an indispensable resource for building strong IT literacy and preparing learners for future digital careers.