So what exactly is the internet? As you might expect for something so important and transformative, there’s no single answer to that question. Instead, there are three.
The internet is a physical network, governed by protocols, that is used by billions of people all over the world. When you combine physical connections, protocol cooperation, and people-generated content, you produce a global phenomenon.
Video by Geoffrey Challen (Assistant Professor, Computer Science and Engineering, University at Buffalo) perfectly explains What is Internet?.
Reference: Part of the https://www.internet-class.org online internet course. A blue Systems Research Group (https://blue.cse.buffalo.edu) production.
Shivraj Marathe 