IP address

What is an IP address?

An Internet Protocol (IP) address is a numerical label (like 203.0.113.43) that identifies a device on a network, and allows computers to talk to each other. Any device on any network will need an IP address so it can receive data from other devices; the IP address is how the network gets data to the right place. Some IP addresses are public, while others are private. Sometimes, your IP address can be used to identify and track you across sites and apps.

What are public and private IP addresses?

A public IP address is one that the Internet can directly deliver data to. A private IP address, by contrast, is one that is only meaningful on a local network, not the Internet.

Merely having a private IP address does not protect your privacy on the Internet. You can’t use the Internet at all without being visibly associated with a public IP address.

As an example, your home Wi-Fi network is a local network. Every device connected to it has a private IP address, specific to your home network. The Wi-Fi router (the device that connects your home to the Internet at large) has both a public and a private IP address, and relays traffic between your home network and the Internet. The router uses its public IP address to talk to the Internet, and its private IP address to talk to your devices on Wi-Fi.

When you visit a website, the Web server (the specialized computer where a website “lives”) only sees your router’s public IP address, not your device’s private IP address. The private address wouldn’t be useful to them, because it can’t be used to get data to the right place on the Internet.

How do I get an IP address?

Your Internet service provider (ISP) automatically assigns public IP addresses to customers. Devices get their public IP addresses from the ISP when they connect to the ISP’s network, such as when you plug an Internet cable into a router.

The router on a local network assigns private IP addresses to devices on the network. When your device connects to that local network, the router will tell it what its assigned private IP address is.

Note: not all addresses are assigned this way. For example, some ISPs allow customers to claim a specific public IP address long-term.

What are the privacy concerns around IP addresses?

When you use any service on the Internet, the service can see the public IP address through which you’re accessing the Internet. The IP address stays the same as you browse, so trackers can use it to correlate your activity across different sites. It’s an imprecise form of tracking—since multiple devices can be on the same Wi-Fi network and thus share the same public IP address—but still a risk.

Also consider that IP addresses are allocated geographically, which means that your public IP address indicates your physical location. It’s not very precise—your public IP address won’t give away the exact spot where you’re standing—but it certainly indicates the country you’re in, and probably even the city.

Privacy concerns and your IP address

Can a VPN help hide my IP address?

Using a VPN can mitigate some of the concerns with IP address tracking. While you’re connected to a VPN, websites you visit will see the VPN server’s public IP address instead of yours. If you connect to a VPN with servers in another country, the public IP address that websites see will be from that other country, rather than where you (and your device) are at that moment. For this reason, some people will use a VPN to get around a website’s geographic restrictions.

Another consideration with VPNs and geographic location is that websites that care which country you’re in—such as streaming video sites that show certain videos only to viewers in certain countries—will use your public IP address to make that determination. You might also see ads that include the name of your city; those are using your public IP address too.

What is IPv6?

IPv6 is a newer version of the Internet Protocol that uses much longer IP addresses. The older, more common version is called IPv4; its addresses are structured as four numbers (with a maximum of three digits each), separated by periods, as in the 203.0.113.43 example shown earlier in this article.

IPv6 addresses, by contrast, consist of eight numbers, each between 0 and 65,535.

Why was IPv6 developed?

The need for IPv6 arose because of a shortage of available IPv4 addresses on the Internet. Since an IPv4 address consists of four numbers between 0 and 255, there are about 4.29 billion possible IPv4 addresses. That’s less than the total number of networked devices in the world, so the Internet industry has had to come up with ways for several devices to share one address. It’s not a future-proof situation.

There are many more possible IPv6 addresses—roughly 340 quadrillion quintillion. That’s an inconceivably large number. The world will never run out of IPv6 addresses.

Is IPv6 good for privacy?

IPv6 can actually be worse for privacy. IPv6 addresses can be tracked more precisely than IPv4 addresses because they aren’t shared between multiple devices.

Devices can try to mitigate that problem by frequently switching to new addresses—which is only possible because IPv6 addresses are so plentiful—but that doesn’t eliminate the privacy risk of more precise IP address tracking.

How can I use IPv6?

To use IPv6, your ISP and router must support it. If your ISP doesn’t support IPv6, there’s nothing you can do. If they do support it, all you should have to do is to make sure that IPv6 is enabled in your router’s settings.

All major operating systems and personal devices support IPv6, and can have both an IPv4 address and an IPv6 address at the same time. If your ISP supports IPv6, your Internet traffic is a mix of IPv4 and IPv6, depending on what websites you visit; some websites don’t yet support IPv6.