It would be hard to imagine an internet that didn't even allow users to send invoices to each other. However, in the beginning of the internet, commercial use was forbidden. The internet was strictly for education and research purposes. It's hard to imagine an internet without sites like E-bay, and Google's Adsense, but it wasn't until the 1990's that these restrictions were lifted.
You see, the internet began as a research project. When the project was completed and the initial internet was created, it was handed over to the Defense Communications Agency a part of the National Department of Defense. Commercial use was forbidden and the network was mostly housed on educational and military locations.
Eventually, the National Science Foundation worked their way in during the 1980's. By the end of the 1980's the Defense Department felt that their job was done and abandoned their role as the backbone of the internet. This left the National Science Foundation in charge and they also did not condone the use of the internet for commercial purposes.
However, many groups debated the definition of commercial use and got away with some infractions. By 1994, the National Science Foundation was no longer the backbone of the internet. Without both the NSF and the Defense Department serving as the backbone, the internet was free for commercial use.
After April 30, 1995, the internet experienced increase growth as the result of the National Science Foundation's move to privatize the network. During the late 1990's many investors began to pour their money into .com businesses that ended up going bust in March of 2000. However, today many people have internet businesses that are doing well. Amazon.com and E-bay are companies that are not only doing well now, but actually survived the .com period without going bust. They also have a great outlook for the future as does many internet companies.