This eBook tells of The journey of IP addressing began with IPv4, which has been the backbone of the internet since the 1980s. Its design was groundbreaking at the time, offering approximately four billion unique addresses, enough to support early internet growth. However, over time, the explosive expansion of connected devices and the proliferation of internet services caused the limitations of IPv4 to become evident. The rigid structure and scarcity of addresses prompted the need for a more scalable solution, leading to the development of IPv6. This evolution was driven by the necessity to meet the demands of an increasingly interconnected world, where billions of new devices constantly come online, from smartphones and smart home devices to industrial sensors. Transitioning from IPv4 to IPv6 has thus become a strategic move to ensure the internet remains robust, scalable, and ready for future growth.