In this two-part article, I trace the history of the Internet.The Internet started in 1969 as an experiment by the AdvancedResearch Projects Agency (ARPA) of the US Departmentof Defense to use packet switching on leased telephonelines to connect four mainframe computers. Email was inventedin 1971 and it became a “killer application” as it promotedeasy interaction among its users. By 1972, fifty computerswere connected using leased telephone lines to formwhat was known as the ARPANET which was successfullydemonstrated at an international conference – ICCC 72.ARPANET was followed by Packet Radio Network (PRNET),which connected mobile computers, and Satellite Network(SATNET), which connected computers in Europe with thosein the US. A protocol named Transmission Control Protocol/Internet Protocol (TCP/IP) was invented in 1973 to interconnectARPANET,PRNET, and SATNET. The success of theTCP/IP protocol in connecting disparate networks paved theway for the development of the Internet.