Actually, the Internet sprang forth from the DARPA funding to find a way for dissimiliar computers to be able to share information in a seamless manner, regardless of the location of the computers.
Thus DARPA-Net was born. The project used, what would be later called, UUCP to trade files between desparate computer systems over 300 baud modems.
The primary use became one where various colleges and universities traded information and discussions. The first program created to automatically store and organize this data was developed at NASA and named 'Notes'. At its peak, the Notes network was pretty large and DARPA had pulled its funding. The project was renamed ARPA-Net and found funding in the various universities and corporations who had become dependent on the information and email capabilites.
Notes was lacking in some areas, and required a full download/upload of the entire tree of data when a new note was posted as the databases were single files with indexes to the information in those files.
As time went on, the number of people joining in the discussions grew and the Notes program was not up to scaling for this. Thus was born uunet (UUCP Network) (later to be named Usenet). By only trading the individual files/posts/emails, the network became much more efficient and about that time 1200 baud modems were becoming the norm.
The network was pretty centralized with server main hubs. The primary hub in this network was a computer named 'ihnp4' which was maintained by AT&T.
With no government intervention or restrictions this network grew at an incredible rate. UUnet was formed as a corporation and was the primary supporter of the network. Links to overseas were exstablished by various companies so thier offshore subsidiaries could communicate with headquarters.
In the mid to late 1980's, the name 'Internet' surfaced. A lot of finger pointing/hand raising goes on as to who named it and how it came to be. It was during this time that modems were being phased out in favor of direct high speed links and the use of TCP was supplanting UUCP. Various gateways between the two networks were available to keep everyone on the 'net'.
In the early 1990's AOL decided to allow thier users access to the Internet and thus the commercialization of the Internet reached staggering heights.
The early days were a lot of fun. The quality of information back then was simply outstanding.