How the Internet Works

What Is the Internet?

At its core, the internet is a network of networks. Billions of devices—from smartphones to servers are connected, sharing information across the globe. But this system wouldn’t work without a shared language.

That’s where protocols come in.

The Role of Protocols

Protocols are like the grammar rules of the internet. They define how data is formatted and transmitted between devices.

Think of it like a phone call. When you pick up the phone and say “Hello,” that’s an example of a protocol in action. It’s a standard, expected way to start a conversation. If both people on the line follow the same conventions—taking turns speaking, listening for cues, using a shared language—the conversation flows smoothly.

+-------------------------+                     +-------------------------+
|       Person A          |                     |        Person B         |
+-------------------------+                     +-------------------------+
| Picks up phone          |  ---- Hello --->    | Receives greeting       |
| Waits for response      |                     | Responds: "Hi there!"   |
| Speaks when it's their turn                  | Speaks when it's their turn
| Uses shared language     <--- Response ---    | Understands message     |
| Ends call with "Bye"     ---> "Bye!" --->     | Ends call with "Bye"    |
+-------------------------+                     +-------------------------+

         📞 Conversation Flow Follows Agreed Protocol
        - Start: "Hello" initiates connection
        - Middle: Turn-taking, mutual understanding
        - End: "Bye" signals termination of session

The most foundational protocol is the Internet Protocol (IP). Every device connected to the internet has a unique IP address, kind of like a digital home address. This address tells the network where to send and receive information—just like writing a street address on a package.

There are two main types of IP addresses:

• IPv4: The most commonly used format (e.g., 192.168.1.1), which allows for about 4.3 billion unique addresses.
• IPv6: A newer standard (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334) that supports a nearly limitless number of devices—essential for the growing Internet of Things.

When you visit a website, your device uses its IP address to request information from the website's server. That server has its own IP address. Routers and other infrastructure use these addresses to ensure that packets are delivered to the correct destination.

Without IP addresses, devices wouldn’t know where to send or receive data—just like a mail carrier wouldn’t know where to deliver a letter without a proper address.

TCP/IP

Alongside IP, you’ll find the Transmission Control Protocol (TCP). Together, they form what's commonly referred to as TCP/IP—a foundational suite of protocols that powers the internet.

Think of it as a layered system:

• IP (Internet Protocol) is responsible for addressing and routing. It makes sure data packets know where to go, kind of like addressing envelopes for delivery.
• TCP (Transmission Control Protocol) sits on top of IP and ensures those packets arrive completely, in order, and without errors.

When you send something over the internet—like a cat meme—TCP/IP breaks the data into smaller chunks called packets. Each packet contains part of the data, along with instructions (like sequence numbers) to help reassemble the full message later. These packets travel independently across the internet, hopping through routers and networks. They may even take different paths to the destination depending on network congestion or availability. Once all the packets arrive, TCP reassembles them in the correct order to reconstruct the original file. This process ensures that, even if packets arrive out of order or take different routes, the end result is exactly what was sent. This is what makes the internet so robust—it doesn’t rely on a single path, and it knows how to recover and organize information even under less-than-ideal conditions.

When a device receives a TCP packet, it sends back an ACK (acknowledgment) to the sender.
This ACK tells the sender:

"I received your packet successfully"

And more specifically:

"I'm ready for the next one"

If the sender doesn't receive an acknowledgment within a certain time
(because a packet got lost or delayed), it assumes the packet was dropped
and retransmits it. This is part of TCP’s reliability guarantees.

How Data Travels

Let’s take a look at what happens when you open a website. Say you type a URL like www.example.com into your browser and hit "Enter." Here’s a simplified version of what’s going on behind the scenes:

1. Domain Name Resolution (DNS): Before your device can even send a request, it needs to find the IP address of the server hosting the website. This is where the Domain Name System (DNS) comes in. Think of it as the internet’s phone book. Your browser contacts a DNS server to translate www.example.com into something like 93.184.216.34, which computers can understand.
2. Sending the Request: Your browser then sends an HTTP (or HTTPS) request to the IP address provided by DNS. This request asks the server for the web page and its resources.
3. Packetization and Routing: The request is broken down into smaller data packets and routed across a series of networks and internet routers.
4. Server Response: The server receives your request and responds by sending back the necessary files—usually HTML, CSS, JavaScript, and media assets.
5. Returning Packets: These files are also broken into packets, which may travel along different paths across the internet before arriving back at your device.
6. Reassembly and Rendering: Your browser reassembles the packets, interprets the code, and renders the complete web page on your screen.

And all of this happens in a matter of seconds, or even milliseconds.

Routing the Packets

Routers are the traffic managers of the internet. They inspect each packet and decide the best path it should take. This path might change depending on congestion, outages, or other network dynamics.

Remarkably, your packets might travel through dozens of cities and countries before arriving on your screen, without you ever noticing.

Where the Internet Lives: Data Centers and the Cloud

As your data packets travel across the internet, their destination is often a data center—a physical facility that houses servers, storage systems, networking hardware, and everything needed to host and deliver web services at scale.

Modern data centers are run by major cloud providers like Amazon Web Services (AWS), Google Cloud Platform (GCP), and Microsoft Azure. These companies operate massive global networks of data centers in locations all over the world.

Rather than every company building and managing their own physical servers, most websites, apps, and platforms today rely on these cloud providers to:

• Host web servers and APIs
• Store data and files
• Run application logic
• Automatically scale to meet demand

These cloud platforms make it easier and faster to deploy digital services—and they provide the flexibility to scale globally without needing to manage hardware directly.

When you visit a modern website, there’s a good chance your request is being handled by infrastructure running in one of these hyperscale cloud data centers.

Scalability: Why Millions Can Request at Once

Scalability is built into the internet’s architecture, enabling it to handle millions of simultaneous users requesting the same content—from trending videos to viral news stories—without crashing or slowing down.

One of the key technologies that makes this possible is the Content Delivery Network (CDN).

What Is a CDN?

A CDN is a globally distributed network of servers that cache and deliver content to users based on their geographic location. Instead of every user having to connect to a single origin server (say, in California), a CDN brings the content closer to them—whether they’re in Tokyo, Paris, or São Paulo.

How It Works:

1. When you request a popular piece of content (like a webpage, image, or video), your request is routed to a nearby CDN edge server.
2. If that server already has a cached copy of the content, it delivers it instantly—no need to contact the origin server.
3. If it doesn’t have a copy yet, it fetches it from the origin, caches it for future requests, and then delivers it to you.
4. This process happens so quickly you don’t even notice it’s being optimized in real time.

Final Thoughts

The internet might feel like magic, but it’s really a masterpiece of global collaboration and technical ingenuity. From IP addresses and data packets to routers and CDNs, every piece plays a part in delivering information faster than ever before.

So the next time you visit a website or stream a video, take a second to appreciate the incredible system working behind the scenes.