SRI International in Menlo Park is party to a birthday today.

On Oct. 29, 1969, a student at the University of California, Los Angeles tried to log on to a computer 400 miles away at SRI, and lo -- which is as far as the student got with the word "login" before the system crashed -- the Internet was born, according to a report on the SRI Web site.

Those two characters were enough to establish a milestone in electronic communication. Many more have followed.

"In the 1960s, as many as a few hundred users could have accounts on a single large computer using terminals, and exchange messages and files between them," said Marc Weber, founding curator of the Computer History Museum's Internet History Program in Mountain View.

"But," Mr. Weber continued, "each of those little communities was an island, isolated from others. By reliably connecting different kinds of computers to each other, the ARPANET took a crucial step toward the online world that links nearly a third of the world's population today."