What Is an IP Address?
Learn what IP addresses are, how they work, and why every device on the internet needs one.
What Is an IP Address?
An IP address (Internet Protocol address) is a unique numerical label assigned to every device connected to a computer network. Think of it as a mailing address for your device — it tells other devices where to send data.
Without IP addresses, devices on the internet would have no way to find each other. Every time you load a website, send an email, or stream a video, IP addresses are working behind the scenes to route data between your device and the server.
How IPv4 Addresses Work
The most common type of IP address is IPv4 (Internet Protocol version 4). An IPv4 address is a 32-bit number, typically written as four decimal numbers separated by dots:
192.168.1.100
Each number (called an octet) ranges from 0 to 255, giving us roughly 4.3 billion possible addresses. While that sounds like a lot, the explosive growth of internet-connected devices has actually exhausted the available IPv4 address space.
The Two Parts of an IP Address
Every IP address has two components:
- Network portion — Identifies which network the device belongs to
- Host portion — Identifies the specific device within that network
The subnet mask determines where the network portion ends and the host portion begins. For example, with a /24 subnet mask (255.255.255.0), the first three octets identify the network and the last octet identifies the host.
Static vs Dynamic IP Addresses
- Static IP — Manually assigned and doesn't change. Used for servers, printers, and network infrastructure.
- Dynamic IP — Automatically assigned by a DHCP server and may change over time. Used by most consumer devices.
Your home router typically receives a dynamic public IP from your ISP, while devices on your home network get dynamic private IPs from the router.
Why IP Addresses Matter
IP addresses are fundamental to how the internet works. They enable:
- Routing — Data packets travel across multiple networks to reach their destination
- Identification — Servers know where to send responses
- Access control — Firewalls and security systems use IPs to allow or block traffic
- Geolocation — IP addresses can approximate a user's physical location