The Internet is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. The Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web (WWW), electronic mail, telephony, and file sharing./wikipedia
source/image: Learn Engineering
The internet works through a massive global network of optical fiber cables. In this animation, you can see how data typically flows between the different levels of internet service providers in the modern internet. watch the video from Learn Engineering for more info:
The optical fiber cables carry signals in the form of light. However, your laptop or mobile phone processes electrical signals.
So how does this conversion of light to electrical signals happen? And more importantly, why is the internet structured the way it is today?