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

IP Addresses: The Internet's Postal System

An IP address (Internet Protocol address) is a unique numerical identifier assigned to every device that connects to a network. Think of it as a postal address for your computer, phone, or any internet-connected device. Just as postal workers need a physical address to deliver mail to your home, the internet needs an IP address to deliver data to your device.

The term "IP" stands for Internet Protocol — the set of rules that governs how data is sent and received across networks. IP addresses are a fundamental part of this protocol, acting as the source and destination labels on every packet of data traveling across the internet.

Without IP addresses, the internet simply could not function. Every time you load a webpage, send an email, or stream a video, your device's IP address is stamped on every packet of data — both as the destination the server should send data to, and as the source the website logs when you connect.

You can check your own IP address right now using our free tool — it will show you both your IPv4 and IPv6 addresses if applicable.

IPv4 vs IPv6: Two Generations of Addressing

There are currently two versions of IP addresses in active use: IPv4 and IPv6.

IPv4 was introduced in 1983 and uses a 32-bit address space, written as four numbers separated by dots — for example, 192.168.1.1 or 203.0.113.42. Each number ranges from 0 to 255. This format allows for approximately 4.3 billion unique addresses. While that sounds like a lot, the explosive growth of the internet has nearly exhausted the available IPv4 space, leading to innovations like NAT (Network Address Translation) to extend its useful life.

IPv6 was developed to solve the address exhaustion problem. It uses a 128-bit address space, written as eight groups of four hexadecimal digits separated by colons — for example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334. IPv6 provides approximately 340 undecillion (3.4 × 10³⁸) unique addresses — enough for every atom on Earth's surface to have its own IP address many times over.

Despite IPv6 being available since 1998, adoption has been gradual. As of 2026, roughly 40–45% of global internet traffic uses IPv6, with the remainder still on IPv4. Most modern devices and networks support both protocols simultaneously in a configuration called dual-stack.

• IPv4: 203.0.113.47 — 32 bits, ~4.3 billion addresses
• IPv6: 2001:db8::1 — 128 bits, 340 undecillion addresses

How IP Addresses Are Assigned

IP addresses are not assigned randomly. A global hierarchy manages address allocation to ensure uniqueness and proper routing across the internet.

At the top is IANA (Internet Assigned Numbers Authority), which manages the global IP address space. IANA delegates large blocks of addresses to five Regional Internet Registries (RIRs):

• ARIN — North America
• RIPE NCC — Europe, Middle East, and Central Asia
• APNIC — Asia-Pacific
• LACNIC — Latin America and Caribbean
• AFRINIC — Africa

RIRs allocate address blocks to ISPs and large organizations, who in turn assign individual IP addresses to end users. When you connect to the internet, your ISP assigns you an IP address from their pool — usually dynamically via DHCP.

You can use our WHOIS tool to look up who owns any IP address block and trace it back through this hierarchy.

Public vs Private IP Addresses

Not all IP addresses are the same. The internet uses a distinction between public and private IP addresses that is crucial to understand.

Public IP addresses are globally unique and routable across the internet. Your ISP assigns your household or business one (or more) public IP addresses. This is the address the rest of the internet sees when you make connections. You can see yours with our IP checker.

Private IP addresses are reserved for use within private networks (home, office, school) and are not routable on the public internet. Three ranges are reserved for private use by RFC 1918:

• 10.0.0.0 – 10.255.255.255 (Class A private)
• 172.16.0.0 – 172.31.255.255 (Class B private)
• 192.168.0.0 – 192.168.255.255 (Class C private — most common for home networks)

Your router bridges these two worlds. It holds a single public IP (from your ISP) and assigns private IPs to all devices on your local network using NAT (Network Address Translation). This is why multiple devices in your home can all share one public IP address. Read our full public vs private IP guide for more detail.

Special-Purpose IP Addresses You Should Know

Beyond public and private addresses, several IP address ranges are reserved for special purposes:

• 127.0.0.1 (Loopback): Known as "localhost," this address always refers to your own machine. It's used by software to communicate internally. Learn more in our loopback address guide.
• 169.254.0.0/16 (Link-Local / APIPA): Your computer assigns itself an address in this range when DHCP fails and no address is available from a server.
• 0.0.0.0: Represents all network interfaces on a local machine. Used in routing tables and server configurations to mean "any address."
• 255.255.255.255 (Broadcast): Used to send a message to all devices on the local network simultaneously.
• 224.0.0.0 – 239.255.255.255 (Multicast): Used to send data to multiple specific recipients simultaneously.

Understanding these special ranges is essential for network troubleshooting and security analysis. Our IP address classes guide covers the full classification system in detail.

Frequently Asked Questions