What is TCP/IP and why does it matter?

TC/IP is an internet protocol
(Image credit: Shutterstock)

Networking technology is an area that is frequently interesting, but it can be complicated. What’s more, figuring out the gritty low-level details of exactly how it works isn't most people's idea of fun either.

In fact, it's often much easier to simply ignore what's happening behind the scenes and get on with accessing the web and using your apps. But, there is one area of networking that deserves a closer look and it centers around TCP/IP.

TCP/IP is the fundamental technology behind how computers communicate across networks. Being able to understand even just a little of how it operates can help you set up your own devices and get them working more effectively. Adding value to your knowledge of TCP/IP is the way it can let you troubleshoot internet issues, configure VPN apps and much more besides.

If you normally prefer to avoid complicated expert-level network speak, we don't blame you - we do too. But, although there's some of that with TCP/IP, you don't have to waste time with endless cryptic jargon. Simply learning a few basic concepts can make all the difference and get you on the way to enjoying a much more effective networking experience.

What does TCP/IP stand for?

TCP/IP stands for Transmission Control Protocol / Internet Protocol. Although these descriptors are often mentioned together, TCP and IP are separate protocols. Used together though, they provide a set of rules that help to define how computers communicate with each other, on both local networks and the wider internet.

The IP part of TCP/IP handles the most fundamental task of getting your data to the source device, whether it's a website, a network printer, or maybe that Xbox in your kid's bedroom.

IP works by splitting your data into chunks called packets, then sending it to the destination. You can think of it as similar to sending a letter. The protocol has two formats of IP address - IPv4 and IPv6 - but the basic operation is the same. In both cases, each letter takes a packet of data to the same address (the IP of your destination server) with the same return address (the IP of your device).

The problem is that, just as in the real world, you've no control over how the letter is handled. Some letters might go by different routes, they may not arrive in the order you sent them, a few letters could be damaged along the way, or some may never arrive at all. This is obviously not great for a networking scenario, although fortunately, this isn't quite as bad as it sounds.

What is TCP?

TCP is, in essence a protocol, which uses IP to send its data, but adds in extra abilities to make sure the system works as you expect.

TCP is connection-based too. So, for instance, it works more like a phone call than the letter we used as an illustration above. It can send streams of data and get acknowledgements from the destination device in real time.

To do this, TCP divides up your data into packets, gives them a number, then sends them via IP to the destination computer.

When your packets reach the destination server, it receives them via IP then passes the data on to its own TCP layer. This is smart enough to detect packet errors and asks for missing data to be sent again. One that happens, the process reassembles your packets, thereby ensuring they arrive in the order they were originally sent. 

This extreme reliability is TCP's big advantage. No matter how many packets you send, or how many different routes they take and, indeed, how many packets are lost, the protocol works hard to ensure your data gets there in the end. Granted, you might have a wait a while if network conditions are really bad, but let's be fair... that's not TCP/IP's fault.

TCP/IP speedups

Incorporating TCP's many features brings some overhead to your data transfers though, slowing you down a little. In a few cases, that may prove to be an issue. If you're using a VPN app, for instance, switching from OpenVPN TCP to the simpler OpenVPN UDP protocol might improve speeds a little. To do this it’s worth checking your Settings box).

Operating systems have their own TCP speedups and settings too. PC experts are frequently able to boost their operating speed by playing around with a Window Auto-Tuning feature, for instance. So there are options available if you’re happy enough to carry out a little bit of tinkering.

If you're not quite so confident, there are freeware tools that can assist with the tweaking process and may well be able to help boost performance. SpeedGuide's freeware TCP Optimizer, as an example, looks scary, but don't let that put you off. Click Optimal and the program claims it can automatically find the best Windows TCP settings, applying them all with a simple click.

A few apps have their own built-in technologies to ramp up your speeds too. The always-impressive ExpressVPN Windows app has an 'Optimize Windows networking to maximize VPN speed' option. So, for instance if you click the “Settings, Advanced” option, the program tweaks some important Windows TCP settings. If it's disabled on your system, turn it on and while it won't work for everyone, this is still well worth a try.

If you want to try any of the options we’ve outlined here do beware, because TCP/IP optimization isn't easy. In fact, it's entirely possible your system will be slower post-tweaking than it was originally. Due to the possibility of this happening, it’s very prudent to make a note of any changes you make so you can restore them later.

If you'd rather stay safe, feel free to leave TCP/IP alone altogether. It's a reliable protocol, which works well out of the box and that is essentially is why it's been powering the web for decades. What’s more, TCP/IP doesn't look like it'll be going away any time soon either.

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Mike Williams
Lead security reviewer

Mike is a lead security reviewer at Future, where he stress-tests VPNs, antivirus and more to find out which services are sure to keep you safe, and which are best avoided. Mike began his career as a lead software developer in the engineering world, where his creations were used by big-name companies from Rolls Royce to British Nuclear Fuels and British Aerospace. The early PC viruses caught Mike's attention, and he developed an interest in analyzing malware, and learning the low-level technical details of how Windows and network security work under the hood.

With contributions from