What Is an IP Address? A Complete Beginner's Guide

An IP (Internet Protocol) address is a unique numerical label assigned to every device connected to a computer network that uses the Internet Protocol for communication. Think of it like a postal address for your device — it tells other computers on the internet where to send data so it reaches the right destination.

Every time you visit a website, send an email, or stream a video, your device uses its IP address to communicate with servers around the world. Without IP addresses, the internet simply wouldn't work — there would be no way for data to find its way to the correct device.

When you connect to the internet, your Internet Service Provider (ISP) assigns an IP address to your device (or more commonly, to your router). Here's what happens when you visit a website:

1. You type a URL (like lookmyip.com) into your browser.
2. Your browser asks a DNS server to translate that domain name into an IP address.
3. The DNS server responds with the IP address of the web server hosting that site.
4. Your browser sends a request to that IP address, including your own IP as the return address.
5. The web server sends the website data back to your IP address.

This entire process happens in milliseconds. Your IP address is included in every data packet you send, which is how servers know where to send their responses.

There are two versions of IP addresses currently in use:

IPv4 (Internet Protocol version 4) uses 32-bit addresses, written as four numbers separated by dots (e.g., 192.168.1.1). This allows for approximately 4.3 billion unique addresses. While that sounds like a lot, we've essentially run out of IPv4 addresses due to the explosive growth of internet-connected devices.

IPv6 (Internet Protocol version 6) uses 128-bit addresses, written as eight groups of hexadecimal numbers separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). This provides approximately 340 undecillion addresses — enough for every grain of sand on Earth to have trillions of addresses.

Most modern networks run "dual-stack," supporting both IPv4 and IPv6 simultaneously. The transition to IPv6 is ongoing but slow, as much of the internet infrastructure still relies on IPv4.

Public IP addresses are assigned by your ISP and are visible to the entire internet. This is the address that websites and online services see when you connect to them. You can check your public IP address instantly using a tool like LookMyIP.

Private IP addresses are used within your local network (home or office) and are not visible to the outside internet. Common private IP ranges include:

• 10.0.0.0 to 10.255.255.255
• 172.16.0.0 to 172.31.255.255
• 192.168.0.0 to 192.168.255.255

Your router uses a process called NAT (Network Address Translation) to allow all your devices to share a single public IP address while each maintaining their own private IP address internally.

Static IP addresses remain the same every time you connect. They're commonly used by servers, businesses, and anyone who needs a consistent address (for example, to host a website or run a mail server).

Dynamic IP addresses change periodically or each time you reconnect. Most home internet connections use dynamic IPs assigned through DHCP (Dynamic Host Configuration Protocol). Your ISP has a pool of addresses and assigns you one when you connect.

Dynamic IPs are more cost-effective for ISPs since they can serve more customers with fewer addresses. For most home users, a dynamic IP is perfectly fine.

Find your public IP: The easiest way is to visit LookMyIP.com — your public IP address is displayed instantly along with geolocation data, ISP information, and more.

Find your private IP on Windows: Open Command Prompt and type ipconfig. Look for the "IPv4 Address" under your active network adapter.

Find your private IP on macOS: Open Terminal and type ifconfig | grep "inet ". Or go to System Settings > Network and select your active connection.

Find your private IP on Linux: Open Terminal and type ip addr show or hostname -I.

An IP address reveals your approximate geographic location (usually accurate to the city level), your ISP, and some basic network information. However, it cannot reveal your exact physical address, your name, or other personal details on its own.

Law enforcement can request your identity from your ISP using your IP address with a court order, but ordinary individuals and websites can only see the general information associated with your IP.

If privacy is a concern, you can use a VPN (Virtual Private Network) to mask your real IP address. A VPN routes your traffic through a server in another location, so websites see the VPN server's IP instead of yours.

Nobody invents their own public IP address. Every routable address on the internet traces back through a four-tier hierarchy, and understanding it explains a lot of otherwise confusing lookup results.

At the top sits IANA (the Internet Assigned Numbers Authority), which holds the global address pool. IANA delegates large blocks to five Regional Internet Registries (RIRs), each responsible for a part of the world:

RIRs assign blocks down to Local Internet Registries — usually ISPs and large hosting companies — which finally hand individual addresses to end users. When a geolocation tool tells you an IP belongs to "Deutsche Telekom, Germany", it is reading the RIPE registration for the block that address falls inside.

This hierarchy is why geolocation is a *network* lookup rather than a *device* lookup. The registry knows which organisation holds the block and what address that organisation filed. It does not know where the individual handset or laptop currently is.

IANA's IPv4 free pool ran dry in February 2011, and the RIRs exhausted their own general-availability pools between 2011 and 2020. New IPv4 space today comes almost entirely from the transfer market, where blocks change hands for roughly $30–60 per address. That scarcity is the direct commercial reason IPv6 deployment keeps accelerating.

Some address ranges never appear on the public internet, and recognising them on sight saves a lot of debugging time. If a lookup returns nothing useful for an address, check whether it falls into one of these:

Two of these come up constantly in support conversations.

169.254.x.x means DHCP failed. If a machine reports this address, it never received a lease from the router. The fault is the cable, the Wi-Fi association, or the DHCP server — not DNS, and not the ISP.

100.64.x.x means carrier-grade NAT. Your ISP has placed you behind a second layer of NAT because they do not have enough IPv4 addresses to give every subscriber one. The practical consequence is that inbound connections cannot reach you: port forwarding will not work, hosting a game server will not work, and the port checker on this site will report every port closed regardless of your router configuration. The fix is to ask your ISP for a public IPv4 address, which most will provide on request, sometimes for a small fee.

IPv6 addresses look intimidating mainly because of the compression rules. They are simpler than they appear.

A full IPv6 address is eight groups of four hexadecimal digits:

2001:0db8:0000:0000:0000:ff00:0042:8329

Two rules shorten it. First, leading zeros in any group may be dropped:

2001:db8:0:0:0:ff00:42:8329

Second, one run of consecutive all-zero groups may be replaced with :::

2001:db8::ff00:42:8329

The double colon can appear only once per address, because a parser reconstructs the missing groups by counting how many are present — with two :: markers that count would be ambiguous.

A few IPv6 patterns are worth knowing on sight:

• ::1 — the loopback address, the IPv6 equivalent of 127.0.0.1.
• fe80::/10 — link-local. Auto-configured on every interface, never routed off the local segment. You will see these in ifconfig output constantly.
• fc00::/7 — unique local addresses, roughly the IPv6 answer to RFC 1918 private space.
• 2000::/3 — global unicast. This is the range that carries actual internet traffic.

In URLs, an IPv6 address must be wrapped in square brackets so the colons are not confused with a port separator: http://[2001:db8::1]:8080/.

One practical consequence of IPv6: because addresses are plentiful, devices generally get a globally routable address rather than sitting behind NAT. That improves connectivity but means a device's address is more directly identifying than an IPv4 address behind a household NAT. Most operating systems counter this with privacy extensions (RFC 4941), rotating the host portion of the address periodically.

Does my IP address change?

Most home connections use dynamic addressing, so it can. In practice it changes less often than people expect — many ISPs renew the same lease for months as long as the router stays powered on. Rebooting the router or a lease expiry are the usual triggers.

Can two devices have the same IP address?

Two devices on the same network cannot; that produces an IP conflict, and both connections behave erratically until one is reassigned. Two devices on *different* private networks routinely share the same private address — 192.168.1.10 exists on millions of home networks simultaneously, which is fine because those addresses never leave their own LAN.

Why does a website think I am in a different country?

The most common causes are a VPN or corporate proxy, an ISP routing traffic through a hub in another country, and stale registry data after a block has been reassigned. Mobile connections are especially prone to this because the carrier's gateway may be in an entirely different region from the tower you are connected to.

Is hiding my IP address legal?

Yes, in most jurisdictions. VPNs, proxies and Tor are legal in the large majority of countries and are used routinely by businesses for legitimate remote access. A handful of countries restrict or ban VPN use, so check local law if you are travelling. Using any of these tools to commit a crime remains a crime regardless of the tool.

What is the difference between an IP address and a MAC address?

A MAC address identifies a physical network interface and is assigned by the manufacturer; it never changes and never travels beyond the local network segment. An IP address identifies a device's position on a network and is assigned by that network. MAC addresses answer "which card is this"; IP addresses answer "where do I send this packet".