What is an IP Address? Plain-English explanation

Short definition: An IP address is a numeric address, such as 192.0.2.10 in the older IPv4 style, that identifies a device on a network and is the destination that a DNS lookup returns for a domain name.

Plain-English explanation

Networks deliver data to numeric addresses, much like postal systems deliver letters to numbered street addresses. An IP address is the machine-readable destination your browser needs before it can open a connection to a website's server. Two versions exist: the older IPv4 style with four number groups, and the newer IPv6 style that provides a vastly larger address space as more and more devices come online.

Why it matters

IP addresses are how internet traffic actually finds its way from one device to another. Knowing what they are clarifies what DNS does, because DNS exists precisely to turn friendly names into these numeric addresses. IP addresses also matter in everyday troubleshooting, since connectivity tools often show them and a wrong or unreachable address is a common cause of a failed connection.

Concrete example

A DNS lookup for info100.cc returns an IP address inside an A record, and the browser then opens a connection to that address in order to load the page. If the returned address is unreachable, the site appears to be down even when the name itself works fine.

Common confusion

An IP address does not identify a person and does not prove who is using a device. Addresses can be shared by many people, can change over time, and can point to different networks, so treating an address as proof of identity or exact location is a mistake.

Related terms

DNS, Domain Name, Server, Website Address

How people actually use it

Devices use IP addresses to establish connections, send packets, and communicate with servers and other devices. Network administrators assign and manage IP addresses to ensure proper network operation and security.

Related terms explained

IPv4

IPv4 is the fourth version of the Internet Protocol, using a 32-bit address space that allows approximately 4.3 billion unique addresses. It is the most widely deployed IP version, but its address pool is largely exhausted.

Example: 192.168.1.1 is a typical IPv4 address used on local networks.

IPv6

IPv6 is the sixth version of the Internet Protocol, using a 128-bit address space, providing a vastly larger number of addresses. It was developed to overcome IPv4 address exhaustion and includes improvements in routing and security.

Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334 is an IPv6 address.

DNS (Domain Name System)

The DNS translates human-readable domain names into IP addresses, allowing users to access websites without memorizing numbers. It is a distributed database that updates as records change.

Example: When a browser resolves 'example.com', it receives the IP address of the hosting server.

Router

A router is a network device that forwards data packets between networks based on IP addresses. It directs traffic from local devices to the internet and manages the assignment of local IP addresses via DHCP.

Example: A home router assigns private IP addresses to devices and sends data to the internet through a public IP.

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More context

IP addresses are essential for routing data across networks; they are assigned by IANA to regional registries, which then allocate them to ISPs. The transition from IPv4 to IPv6 has been ongoing since the 1990s, but IPv4 still dominates due to backward compatibility. IP addresses can also be used to approximate geographic location, which is why they are used in geolocation services.

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