Do you know what was the first message that was sent on Internet?

Scan of ARPANET logic map, circa 1969
Picture Courtesy: Stanford Research Institute (SRI)  International

ARPANET.

The project was started by the Department of Defense’s Advanced Research Projects Agency, then called ARPA and now DARPA. 

ARPANET is the origin of today’s world internet.

The initial ARPANET consisted of four IMPs:

1.  University of California, Los Angeles (UCLA)

2.  The Augmentation Research Center at Stanford Research Institute (now SRI International).

3.  University of California, Santa Barbara (UCSB).

4.  The University of Utah's Computer Science Department.

The first successful message on the ARPANET was sent by UCLA student programmer Charley Kline, at 10:30 pm on 29 October 1969. The message text was the word login; on an earlier attempt the l and the o letters were transmitted, but the system then crashed. Hence, the literal first message over the ARPANET was lo.

 The first permanent ARPANET link was established on 21 November 1969, between the IMP at UCLA and the IMP at the Stanford Research Institute.

By 5 December 1969, the entire four-node network was established.

Source: Wikipedia.