Introduction

This chapter provides a concise historical overview of the Internet’s evolution, emphasizing pivotal transitions in its protocols. It begins with the origins of ARPANET and the shift from the Network Control Protocol (NCP) to the Transmission Control Protocol/Internet Protocol (TCP/IP), marking the first major transition in Internet architecture. The chapter then addresses the ongoing second transition—from IPv4 to IPv6—highlighting the critical limitations of IPv4, including address exhaustion and scalability challenges exacerbated by the Internet’s rapid growth. The depletion of global IPv4 address pools in 2011 underscores the urgency of adopting IPv6 to ensure sustainable network expansion. This chapter contextualizes these transitions within the broader trajectory of Internet development, offering insights for addressing current and future networking challenges.