The internet’s become a crucial part of our daily lives. We use it to connect with other people, stream our favorite songs and TV shows, and even work from home.
But for many of us, how it works remains a mystery. The good news is: It’s not as complicated as you might think. Ahead, we’ll go over a brief history of the internet’s development and explore how it works and its key components.
A brief history of the internet
The concept of the internet goes back more than a half-century:
- 1962 – MIT researcher J.C.R. Licklider presents the idea of a group of computers connected to each other, enabling them to share data and programs together, no matter where each computer was physically located.
- 1965 – Two other MIT researchers, Leonard Kleinrock and Lawrence G. Roberts, connect two computers to each other from across the country using a telephone line.
- 1968 – The Defense Advanced Research Projects Agency (DARPA) expands on their predecessors’ work and creates a system, ARPANET, used to send information between computers.
- 1969 – A host computer connected to a separate computer at UCLA, and then researchers at Stanford connected their computers to the same network, which was part of the ARPANET project.
And so the internet, based on ARPANET, was born. Now that you understand its origins, let’s take a closer look at how it works.
The internet at a glance
The internet is composed of many computers connected to each other and exchanging information. These connections establish what’s known as a “network.” When you connect to the internet, you’re connecting to a huge network consisting of many computers.
How computers talk to each other
So we know the internet is computers talking to each other, but how do they do this? While the way information is sent and received can be complex, the basic structure behind the internet is very simple:
- Computers and other devices have addresses.
- Computers send and receive information to and from each other with these addresses.
- When shared between computers, the information is turned into chunks of data the internet knows how to handle.
- Some computers, called servers, can send out information to other computers upon request.
Computers need hardware to interact with each other, and the hardware they use is controlled by software. If you want to learn more about hardware and the technology that drives computer processing and communication, check out our Learn Hardware Programming with Circuit Python and Computer Architecture courses.
The key components of the internet
The following components are vital to how the internet works:
- IP addresses
- Data packets
- Networking infrastructure
- Internet infrastructure
- Internet routing
- Domain names
Let’s explore each component in further detail.
Computers use Internet protocol (IP) addresses to connect with one another through the internet. Conceptually, they’re similar to the addresses we use to send postal mail.
Every computer has some form of an IP address depending on what network they’re connected to and what they’re doing. For example, your computer may have an IP address that allows information to be sent to it from your printer. It also has another IP address that’s publicly available, which is used while you’re connected to the internet.
When you connect to the internet through your internet service provider (ISP), your IP address is assigned to you, and it identifies your computer, as well as its location. Your computer’s public IP address is used by applications to make sure it gets sent the right information.
In some situations, this can affect the kind of information you receive. For example, Netflix will only show certain content to computers with IP addresses from the United States. If you’ve ever been in another country and connected to Netflix, you may have noticed that the kinds of shows you’re allowed to see are different. This is because your IP address has changed, reflecting where your computer is.
Nodes and hosts
All computers and devices connected to a network are nodes. Hosts are nodes that run applications that send and accept information from other nodes.
As the internet evolved, the connections between nodes got too demanding, and there was a need for new protocols to be developed to make it easier for information to travel. As a result, Network Control Protocol (NCP) and then Transmission Control Protocol/Internet Protocol (TCP/IP) were invented. TCP/IP is used extensively today to make it easier for computers to exchange information.
A protocol is a way of transmitting data between computers and other devices. Computers can’t listen or talk. All they can do is process data, which comes in the form of bytes. These are just strings of 0s and 1s.
The easiest way to understand bytes is to imagine switching a light bulb. “On” is 1, and “off” is 0. These electrical signals cause the light bulb to either illuminate or turn off. Bytes do the same thing, except in far more complex arrangements.
The only way for one computer to turn the bytes sent to it by another computer into something people can understand is to use a protocol. Without protocols, the only thing you’d see on your screen would be hundreds of thousands of zeroes and ones — and even rendering that on your screen would require some sort of protocol.
Here are some of the most common protocols used to send data across the internet:
- Simple Mail Transfer Protocol (SMTP). This is used for email.
- Hypertext Transfer Protocol (HTTP). HTTP is used to connect to web pages on the World Wide Web (WWW).
- Transmission Control Protocol (TCP). TCP routes protocols designed to help run applications to the appropriate app on a computer.
Data packets are how bytes of data are packaged before traveling through the internet. They’re similar to normal packages that contain the parts of something that must be put together.
For example, if you order a bed, the furniture company probably isn’t going to send you the legs in one box, the headboard in a different box, and the frame in another one. All the components are sent in one package. This makes it easier to assemble them into what they’re supposed to be.
And if you order an entire bedroom set, complete with a bed, bedside tables, and an armoire, you’re not going to get one gigantic box with everything in it. Most likely, each major component will be packaged by itself. Otherwise, it would be too hard to deliver — the box would be too huge.
Data packets work in the same way. Instead of one huge file, such as a high-definition movie, being sent in a single transmission, the data is broken up into smaller pieces. Those pieces are put through protocols that allow them to be understood by the computer receiving them. The receiving computer, which may be your phone, TV, or laptop,, understands the protocol and uses it to turn the packets of data into images, text, and sound that you can understand.
Much of cybersecurity, which involves keeping people safe while connected to the internet, hinges on technology that studies data packets. Tools like firewalls can read the information in the data packet and tell if it’s malicious. (To learn more about cybersecurity, check out our Introduction to Cybersecurity course.)
Networking infrastructure refers to the physical devices that networks use to transmit data. In the case of a network set up by your Internet service provider (ISP), the following steps describe how data flows through the networking infrastructure. We’ll use a movie on Netflix as an example and assume the network consists of fiber optic cable.
- The movie, which is on a server run by Netflix, gets sent out to a modem.
- The modem sends the movie data over fiber-optic lines, where it moves as light bounces off the walls of glass tubes.
- Your Internet service provider (ISP) has its own pool of modems, and the one that corresponds with your account gets the movie’s data.
- This gets sent to a port server, which organizes port numbers that serve to identify the transaction as coming from Netflix and headed to your computer, TV, or another device.
- The movie’s data packets go through routers, which are physical devices that forward data to each other.
- The data packets of the movie eventually get routed to your local area network (LAN), which is the modem in your house or another network you’re connected to, such as a café or one at your job.
- The packets then go to your computer, which decodes the data using protocols and shows it to you on your screen, playing the sound that goes along with it.
Sometimes something goes wrong, and what you see doesn’t look right, the sound doesn’t line up, or the video freezes. This is because at some point in the process, between Netflix’s server and your eyes and ears, the data was mishandled by an element of the networking infrastructure or the software that sends and receives the data.
The infrastructure of the internet is built and supported by network service providers (NSPs). By “infrastructure,” we mean the physical components that carry data through the internet. For example, these would include core routers, which take data and send it someplace else, and fiber optic cables, which carry data.
NSP’s install these core components, allowing internet service providers (ISPs) to connect to them. ISPs then provide internet service to people and businesses.
Some popular NSPs include:
- Verizon Business
- Deutsche Telecom
- China Telecom
Some of the major ISPs include:
- Comcast Xfinity
- Time Warner Cable
In order for data to be sent to the right place over the internet, each data packet has routing information that tells it where to go. In this way, data on the internet is similar to mail you send through the post office. Each packet of data has information that tells it where it needs to be sent. Then a router, which sends data along the right route, takes the data, reads the information that says where it’s supposed to go, and sends it there.
Each time the data goes from one router to another, it’s called a “hop.” Eventually, the data hops to your computer or another device.
Obviously, when you connect to a website or web service like Google or Zoom, you’re not typing in the IP address of the computer that provides the data. For example, one of Google’s public IP addresses is 22.214.171.124. While this number is relatively simple, IP addresses are often far harder to memorize.
So if you don’t know the IP address, how do you connect to the server that has the website’s data and services? This is where domain names and domain name servers come in.
A domain name is what you type into your browser, such as “Google.com,” “Yahoo.com,” or “Codecademy.com.” Domain names generally consist of two parts: Top-level domains (TLDs) and second-level domains (2LDs). TLDs are what follow the period in a domain name, like “.com” or other common TLDs like “.gov” or “.edu.”
There are rules and regulations surrounding the use of certain TLDs. For example, “.gov” is typically reserved for governmental organizations. Some TLDs are country-specific, like “.ca” for websites based in Canada or “.de” for those based in Germany.
2LDs precede the period in a domain name. For “Codecademy.com,” “Codecademy” is the 2LD. Generally, a 2LD can be whatever you want it to be — as long as it’s not already in use.
A domain name service takes a table of all the domain names and their IP addresses. Then, it takes what you type in, looks it up in its database, and finds the IP address. This allows you to connect to the site you want.
The internet vs. the World Wide Web
It’s easy to confuse the internet with the World Wide Web, or “the web,” for short. But they’re two distinct things. As described above, the internet is a network of computers connected together and exchanging information with each other.
The collection of websites that use the internet to send and receive data is called the World Wide Web (WWW). In other words, the World Wide Web uses the internet to transmit its data. It needs the internet to survive. But if all websites disappeared, the internet would still exist.
The internet in a nutshell
- The internet is a lot of computers connected to each other exchanging information. Protocols are used to facilitate communications between them and ensure transmissions are sent and that the receiving computers and people can understand the data.
- This data is organized in data packets that get sent using routers from point A to point B. To ensure data reaches the right destination, computers and other devices have IP addresses to which the data gets sent.
- Oftentimes, data is sent to and from websites, which have domain names, like Google.com or Codecademy.com, and a domain name service ensures that IP addresses are associated with the right domain names.
Want to learn more? Try our Introduction to IT course. You’ll learn more about the internet and how it works, along with the basics of networking, software development, and cybersecurity.
And if you want to start building applications that live on the internet, check out our programming courses.