Comment by kragen

The ARPAnet (the electronic system) was never an internet (or catenet). It predated internetworking, and it was one of the networks comprising the internet we are using now (specifically, it was 10.0.0.0/8) until its demise in 01990. As a social institution, though, you are correct: the internet we are using now started out as an experiment inside the ARPAnet project.