... like I'm 5 years old
The Internet, in its most basic form, is a global system of interconnected computers. When you use the Internet to send an email or browse a website, your computer is communicating with another computer somewhere else in the world. That other computer could be a server hosting a website, or it could be your friend's laptop if you are sending them a message. This communication happens via a vast network of physical cables, such as fibre optic cables, and wireless signals, like Wi-Fi and 4G.
Imagine the internet as a giant post office, where instead of letters, we are sending and receiving packets of information. Your computer is like your mailbox, sending, receiving, and sorting these packets.
... like I'm in College
Going a bit deeper, the Internet works on a protocol called TCP/IP (Transmission Control Protocol/Internet Protocol). When you want to send or receive data, like viewing a webpage or sending an email, the data is broken up into small chunks called packets. Each packet is sent individually and may even take different routes to reach the destination. Once all packets reach their destination, they are reassembled in the correct order.
Servers play a critical role in this process. Servers are powerful computers that store the webpages we view, the emails we send and receive, and much more. When you type in a website address, your computer sends a request to the server that hosts that website, the server then sends back the relevant packets of data, which your computer reassembles into the webpage you see.
Imagine each Lego brick is a packet of data. Now, to build a castle (or load a webpage), you need many different bricks (or packets). These bricks are stored in a box (the server), and you are at the other end of the room (the user). To build the castle, you need all the bricks from the box.
Your friend (the ISP) helps you by taking each brick and passing it to you. Sometimes they may throw it (wireless signals), or they may use a little toy car to roll it across (cables). Each brick may take a different path - some may go over the chair, some may go around the table - but eventually, all the bricks reach you.
You then follow the instructions (TCP/IP) to put each Lego brick (packet) in its correct place and voila, you have your castle (or the loaded webpage)!
... like I'm an expert
If we delve into specifics, the Internet is a network of networks, operating on the principle of packet-switching based on the TCP/IP model. The communication begins with your device, which employs an Internet Service Provider (ISP) to connect to the Internet. The ISPs have the infrastructure that can route and reroute the packets of data using a series of protocols.
DNS (Domain Name System) plays a significant role in translating the domain names (like www.google.com) into IP addresses that the network can understand. The Border Gateway Protocol (BGP) is used for routing data across the numerous autonomous systems on the Internet. Internet Exchange Points (IXPs) are physical locations where different ISPs connect and exchange traffic, facilitating efficient data transfer.