IP addressing and subnetting form the foundation of modern network design and are essential for efficient address allocation and routing. Understanding CIDR notation, subnet masks, and address classes enables network engineers to segment networks, optimize IP space usage, and implement security boundaries. The shift from classful to classless addressing revolutionized the internet by preventing IP address exhaustion and reducing routing table sizes—mastering subnetting techniques like VLSM and supernetting is crucial for designing scalable, well-organized networks that balance performance, security, and resource conservation.