Everyone surfing for last-minute Halloween costumes and pictures of black Lolcats today—what you might call the 40th anniversary of the Internet—can give thanks to the simple network message that started it all: "lo."

On October 29, 1969, that message became the first ever to travel between two computers connected via the ARPANET, the computer network that would become the Internet.

The truncated transmission traveled about 400 miles (643 kilometers) between the University of California, Los Angeles, and the Stanford Research Institute.(Watch video about the birth of the Internet.)

The electronic dispatch was supposed to be the word "login," but only the first two letters were successfully sent before the system crashed.