What Is an IP Address?
An IP address is a numerical address used to identify and communicate with devices and services across an IP network, including the internet.
IP stands for Internet Protocol
An IP address is an address assigned to a network interface using the Internet Protocol. It allows data to be addressed and routed between devices across networks.
Think of it as a network address
When data travels across a network, computers need to know where it should be sent.
The Internet Protocol uses IP addresses as part of this addressing and routing process.
What does an IPv4 address look like?
One common type of IP address is an IPv4 address.
It is written as four decimal numbers separated by dots.
Each section represents 8 bits and can range from 0 to 255.
IPv4 addresses are therefore 32 bits long.
How many IPv4 addresses are possible?
A 32-bit address provides:
That is approximately 4.3 billion possible IPv4 addresses.
Not all of those addresses are available as ordinary public internet addresses because portions of the address space are reserved for particular purposes.
What is IPv6?
The newer version of Internet Protocol addressing is IPv6.
IPv6 addresses are 128 bits long and are normally written in hexadecimal.
IPv6 provides a vastly larger address space than IPv4.
IPv4 vs IPv6
IPv4
32-bit addresses written using four decimal numbers separated by dots.
IPv6
128-bit addresses normally written using hexadecimal groups separated by colons.
What is a public IP address?
A public IP address is an address used for communication across the public internet.
For example, a home router may have a public IP address assigned by an internet service provider.
Public IP addresses must be globally routable and cannot simply be duplicated arbitrarily across the public internet.
What is a private IP address?
Devices inside homes and businesses commonly use private IP addresses.
Common IPv4 private address ranges include:
These addresses can be reused on different private networks because they are not routed directly across the public internet.
How can many devices share one public IP address?
Home and business networks commonly use Network Address Translation, or NAT.
NAT allows multiple devices using private addresses to communicate through a smaller number of public IP addresses.
Static vs dynamic IP addresses
Static IP
An address intended to remain fixed unless it is deliberately changed.
Dynamic IP
An address that may be assigned automatically and can change over time.
Internet service providers often assign dynamic public IP addresses to residential customers, while servers and business services may use static addressing where a stable address is useful.
How do devices get an IP address?
On many local networks, IP addresses are assigned automatically using:
A DHCP server can provide devices with information such as an IP address, subnet configuration, default gateway and DNS servers.
IP addresses and domain names
Humans generally prefer names such as:
Computers communicating over IP networks ultimately use network addresses.
DNS helps connect these ideas.
For example, an A record can map a hostname to an IPv4 address, while an AAAA record can map a hostname to an IPv6 address.
An IP address is not a URL
Consider:
This is a URL.
The hostname:
can be resolved through DNS to an IP address.
The rest of the URL identifies the protocol and the resource being requested.
How IP addresses help route data
Data sent using Internet Protocol is divided into packets.
IP packets contain addressing information including source and destination IP addresses.
Routers examine network information and decide where packets should be forwarded next.
What is a subnet?
IP networks can be divided into smaller networks called subnets.
You may see notation such as:
The /24 is CIDR notation. It indicates that the first 24 bits describe the network portion of the IPv4 address.
What is 127.0.0.1?
The IPv4 address:
is a loopback address commonly associated with:
It refers back to the local computer rather than another device on the internet.
Developers often use localhost when testing applications on their own machine.
Does every website have its own IP address?
Not necessarily.
Multiple websites can share the same server and the same public IP address.
Modern web servers can determine which website is being requested from information such as the hostname supplied by the browser.
Can an IP address reveal your exact location?
An IP address can sometimes provide approximate geographic information, such as a country, region or general area.
However, an IP address does not inherently contain a person's exact home address or precise physical location.
Can your IP address change?
Yes.
A device may receive a different IP address when:
Network changes
Connecting to a different Wi-Fi or mobile network can give the device different addressing.
DHCP changes
A dynamically assigned address can change when its network lease changes.
ISP changes
An internet provider may assign a different public address over time.
VPN usage
Internet services may see the VPN server's public IP address rather than the user's ordinary public IP.
The easiest way to remember it
The IP address is therefore one of the fundamental pieces of information used to move data from one network location to another.
An IP address identifies a network destination.
An IP address is an address used by the Internet Protocol to identify network interfaces and route data. IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses. Devices may use public or private addresses, and DNS helps connect human-readable domain names to IP addresses.
