Skip to Main Content

What is TCP/IP and what does it do? 

Most of us like to think that we know all about the internet, but did you know that it’s built on a protocol called TCP/IP? Much like humans, computers need to speak to each other using a common “language”, and TCP is even older than the ethernet! If you’re asking, “What does TCP/IP stand for (and what is the ethernet)?”, you’ve come to the right place. Understanding the technology behind the acronyms can help you better understand how your computer connects to other systems. You can also help keep your connection more secure with free Avira Phantom VPN.  


What is TCP/IP and what does it stand for? 

Without some common rules and frameworks, society would soon descend into chaos and it’s no different with today’s online world. TCP/IP is a communications standard—a set of common rules—that governs the format of data as it’s sent over the internet or other network. It stands for Transmission Control Protocol/Internet Protocol (thank heavens for snappy acronyms) and allows computers to communicate on a network because they all speak the same language. If you’re literally going to split hairs…sorry, protocols, it’s not a single protocol but an entire suite of them. You can   also refer to a TCP/IP “stack”, which is another word for an internet protocol suite.   

If you’re still wondering “But why should I care?” consider for a second what you usually use your computer for. Sending emails? Posting updates on social media? Streaming Netflix? Most computers only become truly useful and meaningful when they can communicate with other computers, often from different companies and in different parts of the world. These connections involve a multitude of people, programs, systems, and languages… and what a global muddle it would be if there was no agreed-upon standard of communication. 

We started with this chaos. Initially, the computers from every vendor had their own way of communicating but the limitations of this soon became obvious. TCP/IP was developed during the Cold War when the U.S. Department of Defense wanted to connect computers within their networks and with each other across national boundaries. They aimed to create a system that would specify exactly how computers would transfer data from one device to another—with military precision so to speak—which is why TCP/IP has always emphasized uniformity and accuracy. It was formalized by DARPA (the Defense Advanced Research Projects Agency) in the late 1960s and adopted as the early protocol standard for its ARPANET, the predecessor to today’s internet. TCP/IP was then adopted by government agencies and universities worldwide and is now the global standard for internet communications today.  

To help understand how it works, cast your mind back to the old telephone exchanges that you might still see in movies. An operator manually connected wires to make an electronic connection between handsets. Once this had been done, the (voice) data could move over this path. TCP/IP is based on a similar concept but uses connectionless data that’s broken into multiple chunks called “data packets”. Like a physical parcel in a postal sorting office, each chunk is then sent to its destination using the best route available.  

What does TCP/IP do? 

It’s the communications protocol that powers the internet, so TCP/IP is required to work reliably and to transmit data accurately. In other words, the recipient must get what the sender originally sent! TCP/IP uses several steps to help achieve this. Let’s head back to the virtual post office that’s handling those data packets. TCP/IP breaks each message down into chunks and then reassembles them into complete messages when they arrive at their destination.  

While all this breaking down and reassembling might sound like a waste of time, imagine what would happen if a whole message was sent as one piece and it ran into problems? Nothing would arrive. With TCP/IP, the data packets take different routes to the other computer. If one pathway is broken or congested, these nimble parcels can zip along another path. If a single one is lost, there may be a small blip, but the rest of the data conversation can continue. This automatic rerouting and resilience are the cornerstones of TCP/IP. 

It’s important to note that data isn’t exploded into random chunks for sending, but carefully divided up via a four-stage process. See below to understand why the TCP/IP model is like a wedding cake with multiple tiers.  

What is the TCP/IP model and how does it work? 

Whether you’re sending a message, file, or photo over the internet, it’s processed in the same way: via a four-layered procedure. When it’s sent, data moves through each layer in a specific order, and it then moves back through these layers in the reverse order when it’s reassembled upon arrival. These methodical steps are how the TCP/IP process is standardized and why the system works so accurately and efficiently. Layers can be updated to enhance performance or security, but no shortcuts or creative deviations are allowed! 

Now let’s delve into the four layers. Each has its own function and together they’re called a “suite of protocols” (or stack):  

Layer 1: Network access  

This first layer includes ethernet cables, network interface cards, device drivers…all the parts of a physical infrastructure that allow computers to communicate with each other using the internet. The technical infrastructure, including the code that converts digital data into transmittable signals, is also situated here. This layer is also known as the data link layer or physical layer. 

Summary: Are there physical parts involved in sending and receiving data? That’s the first layer.    

Layer 2: Internet 

The internet layer is also known as the network layer, and it controls the flow and routing of traffic to ensure that data travels quickly and accurately. This is also where the data packets are reassembled when they reach their destination.  

Summary: Are data packets moving around like they’re being carried by a high-speed postman? Welcome to the second layer.  

Layer 3: Transport  

Here, data is divided into packets ready for sending. The transport layer also acknowledges the packets it receives from the sender and makes sure that the recipient confirms receiving the packets.  

Summary: Imagine a signed-for delivery service. 

Layer 4: Application  

The application layer sits at the top of the TCP/IP architecture and includes all the processes needed to deliver data, such as email, messaging apps, and cloud storage programs. Most of these processes are user services, so it’s what the end-user interacts with when sending or receiving data. 

Summary: It’s at your fingertips when you need to post a photo of your cat.   

What’s the difference between TCP and IP? 

They’re separate computer network protocols and both are vital to seamless online communication. They’re also the perfect partners with very different roles.  

Here’s TCP in action: As it stands for Transmission Control Protocol, the name should give you some idea of what it does: deliver data reliably via a stream of bytes. When you land on a website, for example, a server sends an HTML file to your computer. This happens via a specialized protocol called HTTP which instructs the TCP to activate the connection and send the (right) file. Once it gets its orders, TCP breaks the file up into data packets, labels each packet with numbers, and dispatches them. The data doesn’t travel to the recipient—yet! Instead, it makes a first stop at another vital protocol: IP. Then the packets all take different routes until they reach the same destination. TCP waits until all the packages in the expected “delivery” arrive and then confirms the transfer (or requests a retransmission).  

Here’s what IP does: The Internet Protocol assigns IP addresses to devices on a network so that it can control where the data is headed. So, routers get both the data and the destination IP address. Without this information, it would be like a sad postman wondering through a city without a delivery address. Similarly, data packets would be lost in transit without a fixed destination. Unlike our home addresses though, each IP address is a string of numbers and possibly letters. Although the numbers appear to have been assigned randomly, there is a (mathematical) method to the madness. The address is allocated by an international body, the Internet Assigned Numbers Authority (IANA). Although it does a vital job in keeping our virtual world turning, most of us have never heard of it. If you’re wondering why IP addresses are a long string of numbers but websites have real names, you can thank the Domain Name System (DNS). It converts IP numbers into text as human brains tend to find words more memorable.  

TCP and IP are usually used together as “TCP/IP” because they go hand in hand. TCP carries out the data delivery and IP is responsible for the address where that data is headed.  

Beware! Your data packets are not private! 

Data packets can be seen and read by others as they speed along virtual highways. That’s why it’s highly recommended to use a virtual private network or VPN to help protect your online privacy and help make your surfing more secure. A VPN achieves this by encrypting data so that it can’t be read by third parties even if it is intercepted. It’s especially vital to use a VPN, like Avira Phantom VPN, if you’re sending personally identifiable information, like your home address, or confidential financial information. Never be tempted to send sensitive data on a public Wi-Fi! You never know who’s watching! 

A VPN also redirects your data via a tunnel between your device and the internet so that your real IP address is masked. When your data is transmitted, it will appear to come from the VPN server and not your personal device.  


Are there different types of IP addresses? Does TCP/IP work with all of them? 

Yes, there are various types of IP addresses but before you worry about using the “wrong” one—don’t! Whatever IP address you use, it should work with TCP/IP. All IP addresses fall into one of these four categories, and have their own unique characteristics and uses: 

  • Public IP addresses are assigned to a device by the internet service provider (ISP) to help identify that computer on the public internet. 
  • Private IP addresses are assigned to devices on a private network, such as a home or office network. 
  • Static IP addresses must be applied for at your ISP and don’t change. They’re usually used for services that need a consistent address, such as hosting a website or running a mail server. 
  • Dynamic IP addresses are used by most devices and are always changing. They are assigned by the network every time a device connects to the internet. To learn more about the differences, read up on static and dynamic IP addresses here 

There’s also a new version of IP address called IPv6. The traditional IP address was an IPv4 (Internet Protocol version 4) and it comprises four sets of numbers, each ranging from 0 to 255, and separated by periods. IPv4 was developed in the 1980s and because it has a theoretical limit of around 4.3 billion addresses, no-one was panicking about running out. By the late 1990s, however, this is precisely what was happening. Enter IPv6, which utilizes the extraordinary numerical muscle of 128-bit addresses formatted as eight groups of four hexadecimal numbers separated by colons, so it’s unlikely we’ll be running out again (experts agree that 340 undecillion addresses are probably enough).  

Currently, both new and old formats are peacefully co-existing but IPv4 is being gradually phased out in favor of the bigger, bolder IPv6. You can delve further into the story of IPv4 vs IPv6 here 

Do I need to set up TCP/IP? And what is my TCP/IP address? 

Not usually, thank goodness, as it’s built in as standard in the vast majority of computers, so no manual set-up is required. In fact, TCP/IP is so taken for granted that even though it’s the most used protocol on the web, most people go about their lives online not even being aware of it.  

Every computer has its own TCP/IP address and usually it can communicate its address automatically. Simply connect to your local wireless network and you’re ready to go! Sometimes however, you may need to tell an application what your TCP/IP address is. Here’s a quick way of finding it: Head to your favorite search engine and type in the phrase “what is my IP address”. There are also free online IP look-up services like that search for public registry results.  

While it’s usually simple to find a public or external IP address, if you’re looking for a local (internal or private) IP address, you’ll need some more detective skills. The steps will depend on your operating system. For example, here’s how to find your IP address on Windows 11:  

  1. Open the Windows Start menu and click Settings. Then select Network & internet in the left panel. Open Windows Start > Settings and select Network & internet on the left to start finding your local IP address on Windows 11.
  2. Click on Properties
    In Windows 11 Network & internet settings, click Properties to view your IP address.
  3. Scroll down to see your local IP address, or both your IPv4 and IPv6 addresses. 

Is there an alternative to TCP/IP? Yes! Meet OSI  

Did you know that there’s another protocol that allows computers to communicate over a network? It’s called the Open Systems Interconnection (OSI) model and contains (gasp) seven layers. It was the first standard model for network communications and was adopted by all major computer and telecommunication companies in the early 1980s. Things were looking good for OSI but then the modern internet opted for the simpler four-step TCP/IP model. That’s not to say that there isn’t a place for OSI. It’s still used, mainly to help visualize how networks operate, and to help troubleshoot networking problems. 

Help shield your privacy online with Avira Phantom VPN  

While TCP/IP is the most common protocol, it’s not the most secure. Even a few minutes on public Wi-Fi and you may have unwittingly shared your confidential information. That’s why security experts recommend using a VPN, like Avira Phantom VPN, which utilizes the industry-standard AES 256-bit encryption. This is considered more secure than standard TCP or IP protocols.  

A VPN helps mask your IP address so others can’t view your online activities. It can also help you reclaim your privacy by encrypting your connection to the internet. Then trackers, cybercriminals, and other unwanted third parties can’t eavesdrop on the websites you visit and the data you share. They’re also less likely to be able to hoover up your details to gain access to your online accounts later. If your online privacy is a priority, a VPN is essential.  


This post is also available in: GermanFrenchItalian

Avira, a company with over 100 million customers and more than 500 employees, is a worldwide leading supplier of self-developed security solutions for professional and private use. With more than 25 years of experience, the company is a pioneer in its field.
Avira logo

Who’s watching you online? Surf more securely and anonymously with Avira Phantom VPN!

Avira logo

Who’s watching? Surf more securely and anonymously with Avira Phantom VPN for Mac.

Avira logo

Who’s watching? Surf more securely and anonymously with Avira Phantom VPN for iOS.

Avira logo

Who’s watching? Surf more securely and anonymously with Avira Phantom VPN for Android!