I'm not sure how old you are but I remember using the internet back when they had BBS's.  I really enjoy what it has evolved into.  How about you?
I do not start to use the internet early but the fact that some interconnected computer networks that use the Internet protocol suite (TCP/IP) to link devices worldwide can send and receive information is a breakthrough. 
I agree - quite a break through for humans.  They finally had a spot to exchange information instantaneously.  It's interesting to think about days before it was widespread.  What did people do with their free time?
Computer network
A computer network is a digital telecommunications network which allows nodes to share resources. In computer networks, computing devices exchange data with each other using connections (data links) between nodes. These data links are established over cable media such as wires or optic cables, or wireless media such as Wi-Fi.
Network computer devices that originate, route and terminate the data are called network nodes. Nodes are generally identified by network addresses, and can include hosts such as personal computers, phones, and servers
of interconnected computer networks that use the standard Internet protocol suite (often called TCP/IP, although not all applications use TCP) to serve billions of users worldwide.
- World wide web – part of the Internet; system of interlinked hypertext documents accessed via the Internet.
- Wireless computing – any type of computer network that is not connected by cables of any kind.
- Mobile computing – form of human–computer interaction by which a computer is expected to be transported during normal usage.
- Computer