Packets instead of lines
A telephone network connects two people with one line. ARPANET split data into small packets that could travel different routes and be reassembled at the destination. If one route failed, packets took another. The internet still works this way.
LO
UCLA student Charley Kline was typing the word LOGIN into the SRI computer. After L and O the system crashed. So the first message of the internet age was “LO”, as in “lo and behold”.
Growth
By the end of 1969 the network had four nodes. Email arrived in 1971, the network switched to TCP/IP in 1983 and more networks joined. That became the internet.