1970s

1970: A network is established

An Arpanet network is established between Harvard, MIT, and BBN (the company that created the "interface message processor" computers used to connect to the network).

1971: Email

Ray Tomlinson develops email in 1971. He also decides to use the "@" symbol to separate the user name from the computer name. This later becomes the domain name.

1971: Project Gutenberg and the birth of eBooks

Michael Hart begins Project Gutenberg dedicated to making copyright-free works available in electronic form. In effect, this was the birth of the eBook.

1973 Ethernet

Bob Metcalfe develops ethernet technology.

1974 TCP/IP

Bob Kahn and Vint Cerf develop TCP/IP.

1975: The email client

John Vittal, a programmer at the University of Southern California, develops the first modern email program (MSG). "Reply" and "Forward" functions are added.

1979

Usenet bulletin board is created to exchange information between two North Carolina universities.
CompuServe is created as a service for computer time-sharing. Development for it began in 1969. By 1982 it is available for corporate use.

Sources:

A people's history of the internet: from Arpanet in 1969 to today

The History of the Internet in a Nutshell

History of the Internet