Arpanet (Advanced Research Projects Agency Network) is a research relationship, established by the research firm ARPA. This network is a precursor to the Internet, while the Internet was created by connecting other networks on this. Milestone in the transformation of this network makes the development of the Internet TCP / IP protocol. TCP / IP protocol is a link that allows communication between two or more computers. Determined to act on that computers communicate (TCP) and how to connect computers (IP) in the network. On the TCP / IP based Internet.