For the past few decades, devices connected to the internet – including PCs and websites themselves – have used version 4 IP addresses (IPv4). IP stands for internet protocol and version 4 has been in use since 1983.

Until recently it has been great, but the format which goes something like this - 87.186.240.13 – only allows for 4.3 billion different combinations.

There are a lot more than 4.3 billion devices connected to the internet nowadays, and this is a problem. It’s not yet critical because there are various technologies which allow devices to share one IP address (your broadband router, for example, and subnets) but at some point soon IPv6 will begin to take over. It has to in order to connect new devices to the internet.

The first websites moved to IPv6 back in 2012, such as Google, Facebook, YouTube and Yahoo. And yet, experts are predicting that IPv6 won’t be ‘mainstream’ until around 2035. Essentially, IPv4 and IPv6 will be both be used for a very long time in tandem, despite being incompatible with each other.

As you can probably guess, IPv6 allows for a lot more combinations: 2128 to be exact, which is a number that is too big to express in any other way (ask the Google Assistant “what is two to the power of 128?” if you want to hear the comical answer).

That’s because it is a 128-bit address, rather than the 32 bits of an IPv4 address.

Do I need an IPv6 address?

No. Not right now. You can still access websites such as Google and Facebook because they support both IPv4 and IPv6.

The easiest way to understand it is the difference between calling someone on their mobile phone or landline. They both connect you to the same person, but are different communication methods.

It’s the same with IPv4 and IPv6, and since virtually all websites still support IPv4 connections, you can browse the web and access online services with no problems.

How do I get an IPv6 address?

You might already have one. It all depends on your ISP. If you have a Windows computer, type cmd into the search box and press Enter.

Now type ipconfig and press Enter.

What is IPv6

You’ll see your IPv4 address in the list and maybe one or more IPv6 addresses.

Your phone might have an IPv6 address too. You can see this if you turn off Wi-Fi (to ensure you’re connected to your mobile ISP) and browse to whatismyip.com

This will show your public IPv4 and – if it exists – IPv6 address.

What is IPv6

If you have both, it means that you can access all websites no matter which IP version they use.

If you don’t have an IPv6 address, you won’t be able to view any IPv6-only websites, but your ISP will almost certainly filter them out of web searches so you don’t see results that you can’t access.

Less than 20 percent of all sites use IPv6 currently, and it’s extremely rare to find one that only supports IPv6, so the bottom line is that even if you don’t have IPv6, it’s no problem.

Why should I care about IPv6 then?

If you use a VPN, IPv6 becomes an issue. Most VPNs don’t support IPv6 and block it entirely because only IPv4 traffic can travel through the VPN tunnel. But not all VPNs are equal.

If your VPN doesn’t support IPv6 and doesn’t properly block it, your IP address could leak. This means your location and – possibly – your identity can be discovered, precisely the things that a VPN is meant to protect you from.

So it’s worth running an IP leak test to see if your VPN is leaking your real IP address. It's leaking if the test displays one of your real IP addresses (either IPv4 or IPv6) rather than showing the virtual addresses assigned to you by your VPN.

If it is leaking, you should stop using it and find a better VPN service.