Public computer networks existed in the 1960s (e.g., Tymnet and others
from ITT, IBM, etc.) and I was using the ARPANET circa early 1970s. An
old ARPANET map I recently found and scanned:

<thadlabs.com/FILES/ARPANET_Sept_1982.pdf>

StarLAN (1Mbps Ethernet over existing 2-wire telephone cabling) was a
joint development of AT&T and HP circa 1980 and you can read about my
home StarLAN network in the O'Reilly "Managing uucp and Usenet" book.

"Basic" Ethernet appeared in 1972 and became IEEE 802.3 in 1980.

I recall using the world's fastest computer at the time (1972), an
IBM 360/195 at the Rutherford High Energy Labs about 90 miles north
of London UK, from my home in Silicon Valley over the ARPANET.

The public was on the Internet by the early 1980s via portals run by
The Well, Portal, BIX, GEnie, and many others.

The first web browser was Mosaic circa 1993. By 1994 commerce began
on the Internet and I remember buying some modems from, you're not
going to believe this, www.internet.com, which was located in Palo
Alto CA. Amazon.com started in 1994 and went online in 1995.