How The Internet Works

OR...Oh, Oh, It's Magic!

how the Internet works
Shawn Stewart

Shawn Stewart

Mr. Stewart has 25 years of experience with hundreds of international, commercial, military, and government IT projects. He holds certifications with ISC2, Cisco, Microsoft, CompTIA, ITIL, Novell, and others. He has a Masters in Cybersecurity, a Bachelors in IT, a Minor in Professional Writing, and is a published author.

how the internet worksHard to believe that the Internet is nearly 30 years old. Sure, AOL, CompuServe, and Prodigy had dial-up available in major cities as early as 1989 to their own internal services, but most households didn’t use a Netscape browser across a modem line to reach the World Wide Web (WWW) until the mid-90s. Learn about the history of the Internet here. (Link)

Can you remember how the world worked before the Internet? I can, but I’m old. As pervasive as it is with refrigerators going online to update shopping lists, many still don’t understand how the Internet works.

Simple. Your kids do it all the time on your phone, their tablet, or home computer. All they have to do is open the browser, whether it’s Chrome, Safari, or Edge, and, BAM, the entire world is at their fingertips. But how does it actually work? Let’s compare it to something everyone is familiar with, the US Postal Service.

In order to receive mail, you must have an address. You can use a post office box if a mail carrier doesn’t come to your physical location. Either way, you must have an address to receive a package or letter. In order to send mail, you also should have an address listed as the return. This is the basics of postal communication. A person at one address can speak to a person at another address.

Mail Carriers To Data Carriers

The Internet, and all computer interactions, work exactly the same way. If you want to communicate on the Internet with anyone, you need an address. How do you get an address? You sign up for Internet service with an Internet Service Provider (ISP). Comcast, AT&T, and Spectrum are all ISPs that give you access to the Internet. We are spoiled by our cell phone carriers, since each of them is also an ISP providing Internet access. Verizon, AT&T, and T-Mobile are the primary carriers in the US. All others, like Mint, Cricket, and Consumer Cellular, resell access to the big three.

how the internet worksDuring the dial-up days, you connected your phone line to a modem (MOdulator/DEModulator) and called a carrier. The carrier confirmed your login and gave your computer an Internet Protocol (IP) address. The IP address is like your postal address. But instead of sending letters and packages, you are communicating with Packets. Packets are tiny blocks of data sent by the millions every second, back and forth, across the Internet.

Carriers bring the line straight into your house or business. No need for a modem and phone line. However, the carrier only gives you one single IP address per house. But, you have five cell phones, two wireless access points, four televisions, three laptops, two tablets, four Echos, two Ring doorbell cameras, a Playstation, and four FireSticks. How can all those devices use the same address?

Routers To The Rescue

This is where the Router comes in. Every carrier will rent or sell you a network router to interface with their line. The device often doubles as a Firewall, which prevents anyone from the outside from getting into your internal devices. The router hosts the single IP address for communications to and from the carrier. It also gives a private range of IP addresses to every device internally. These addresses cannot communicate with the Internet without the router. The router creates a separate communication string for each internal device using address translation.

how the internet worksWithout using confusing technical jargon, think of a single address for an apartment complex as the router and each device has it’s own apartment number. When mail arrives, the local mail person knows which box to put each apartment’s mail in. They act as the gatekeeper. The router is your Internet gatekeeper. When you open YouTube on your laptop, the router assigns the traffic flow to a specific network port and to your internal device IP address for that data flow. Each different data flow to a different destination uses a different port. There are up to 131,070 (TCP and UDP) ports available for the router to use.

The router also gives you two other important pieces of information that are required for Internet traffic. The first goes along with your private IP address range called the default gateway. The default gateway is the router. While its public-facing IP address can communicate with the Internet, its private IP address can only communicate with the internal devices. Internal devices can communicate with each other because they are all on the same address range (Intranet or Intra-Network). When they want to communicate outside the internal network, to the Internet (Inter-Network), all traffic is sent to the router, or default gateway.

Names To Numbers

The second piece of information is a Domain Name Service (DNS) address. DNS is a service of the Internet Protocol that converts human-readable names, like, to its IP address. All communications on the Internet only use IP addresses. When you type into FireFox, your computer reaches out to the DNS address provided and asks, “what is the IP address for” The DNS service returns, one of Facebook’s many addresses. Then the computer requests to access that IP address through the router.

The Beauty of Networking

how the internet worksUsing routing protocols, the request from your computer to your router hops across the Internet to its destination. Your router looks to see if the destination IP address is directly connected to the local IP network. If not, it asks its default gateway, or default route, to pass the request along. There are thousands of routers across the major carriers that interconnect to move traffic from one place to another. Think of connections at the airport or taking the subway from Newark airport to north Bronx. You can’t always go straight. Sometimes you have to make several hops. The Internet routing system is a giant subway with billions of stops.

Once the routers find the correct path from your computer to Facebook, they process your two-way packets at lightning speed. No, really. The primary limitation on today’s Internet devices is the speed of light. Millions of packets process, back and forth, just opening the initial Facebook feed on your browser in seconds. Data streams, like online gaming or YouTube videos, can generate hundreds of millions of packets, based on the size of your carrier connection. In reality, Internet connections are not measured in speed but transfer rate.

Bits or Bytes?

Internet Service Providers have two “speed” designations, Megabytes (MB) and Megabits per second (Mbps). One (1) byte equals eight (8) bits. If your Internet connection is 80 Megabits per second, your actual download speed is 10 Megabytes, which is how computers calculate and show throughput. Nearly all providers measure transfer rates in Megabits per second. The chart below shows typical bandwidth requirements. How much bandwidth does your home or office really need?

Bandwidth Usage Chart

KB = Kilobytes per second
MB = Megabytes per second
Mbps = Megabits per second

  • Streaming Video – Standard Definition (per stream) – 375 KB
  • Streaming Video – High Definition – 625 KB
  • Streaming Video – Ultra/4K – 3.125 MB
  • Streaming Audio – 64 KB to 250 KB
  • Email (average) – 100 KB
  • Conferencing Audio – 64 KB
  • Conferencing Video – 720 KB to 1 MB
  • Screen Share – 350 KB to 720 KB

Remember the list of devices from earlier? Two 4K televisions streaming at the same time require at least 6.25 Megabytes of bandwidth, or 50 Megabits per second. That will max out a standard Internet connection at home. Internet slow? Try the tips in this blog (Link). Also remember that Upload speeds are often asymmetrical, meaning your 50 Megabits per second download may only upload at 10 Megabits per second.

Basic Internet Protections

how the internet worksI hear the questions. How do hackers get in from the Internet? Usually, they don’t. Most hackers aren’t wasting time trying to break into your router. They look for devices that have known vulnerabilities. Your biggest entry point for hackers in a home network is either phishing links in email or SMS text messages on your phone or Drive by Downloads. You can learn more about phishing here (Link).

Drive by Downloads are malicious programs that load when you visit unsafe websites. It’s not just porn and illegal download sites. Clickbait sites are teeming with malicious software. What is Clickbait? They are easy to spot. They include phrases like “one weird trick” or “the King does this every day”. They are interesting but unnecessary websites that are typically trying to sell some snake oil or magic potion to lose weight, grow hair, or cure an ailment. Best bet is to stay away from them and purchase a good end-point security software, like Kaspersky, Bitdefender, or Microsoft Defender. Free security software is not regularly updated or safe.


Internet communications require a unique public IP address. DNS allows the conversion of human-readable names to IP addresses. Routers form the backbone of the Internet and allow packets to flow anywhere in the world. Most carriers designate speeds in Megabits per second, which is one-eighth the bandwidth of Megabytes. End-point software should be on ALL compatible devices. The first step to losing weight in the new year is to stop drinking your calories and carbs and take a walk.

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