<human>:  Tell me about the history of the internet.
<bot>: The internet has a long and winding history that began in the mid-1960s. The idea of the internet first appeared in ARPANET, a research project of the Advanced Research Projects Agency (ARPA), an arm of the United States Department of Defense. In 1969, the first message was sent over the network from UCLA to Stanford Research Institute. It said "LOGIN." Over the next few years, other universities and research centers began connecting their computers to this network and creating a number of proto-networks. By the late 1970s, some of the networks had merged to form the first international networks, such as UUCP, JANET, X.25, and CSNET. In 1983, ARPANET was replaced by the modern Defense Data Network under the United States Department of Defense, or DoD. The formation of the Internet as we know it today began with the TCP/IP protocol, which was released in 1984. In the early 1990s, commercial service providers started to appear, followed by the appearance of the World Wide Web in 1993. The number of connected users on the internet surpassed 1 billion in 2005 and continues to grow rapidly today.