Definition:
An IP address is a numeric label assigned to a network interface so that it can send and receive data using the Internet Protocol. It appears as the source or destination in packets and allows routers to forward them between networks.
IP stands for Internet Protocol, the set of rules that defines this exchange of packets. The address identifies a connection point within a network, but it does not necessarily correspond to a person, an entire device or an exact physical location.
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How an IP Address Works
When an application communicates over the Internet, data is divided into packets that include a source address and a destination address. Routers examine the destination’s network prefix and select the next part of the route until each packet approaches the relevant network.
The DNS allows domain names to be used instead of memorising numbers. It resolves a name such as example.com to one or more IP addresses, but this translation and IP addressing perform different functions.
The same machine can have several addresses because it has different interfaces, uses both IPv4 and IPv6 or connects to more than one network. Several devices can also share one public IP address when a router uses Network Address Translation, or NAT.
Versions of the IP Protocol
Current networks use two main versions. They are not two ways of writing exactly the same address, but protocols with different address spaces and headers:
- IPv4: It uses 32-bit addresses, normally represented as four decimal numbers separated by dots, such as 192.0.2.53.
- IPv6: It uses 128-bit addresses written as hexadecimal groups separated by colons, such as 2001:db8::53. Its current specification is RFC 8200, which replaced RFC 2460.
These examples belong to blocks reserved for documentation. The technical coexistence of IPv4 and IPv6 can use dual stack and other transition mechanisms while networks and services adopt IPv6.
Addressing Scopes
An address’s scope determines where it can be used and routed. This classification is separate from whether the assignment is static or dynamic. Common scopes include:
- Public address: It can be announced and routed over the Internet. This is the address that an external service normally observes when it receives a connection.
- Private address: It is used inside local IPv4 networks with the blocks defined in RFC 1918 and is not routed directly over the Internet.
- Local address: IPv6 provides unique local addresses for communication limited to one or more sites, without an expectation of global routing.
- Link-local address: It operates only on the immediate network segment and supports local operations without crossing routers.
In many IPv4 networks, NAT translation connects several private addresses to one or more public addresses. This mechanism conserves public space, but it also means that the address visible from the Internet does not directly identify the originating device.
Address Assignment
The IANA coordinates global address spaces and allocates large blocks to five Regional Internet Registries: AFRINIC, APNIC, ARIN, LACNIC and RIPE NCC. RIRs distribute resources within their regions to operators and organisations. This hierarchical allocation allows routes to be aggregated by prefix.
An interface can obtain its address in several ways:
- Static configuration: It is set manually to keep an address stable within the managed environment.
- Dynamic assignment: A DHCP server, provider or autoconfiguration mechanism supplies an address that may change over time.
- Prefix delegation: An operator assigns a network a block that can be divided into subnets for its different segments.
A dynamic address does not have to change with every connection, and a static address is not necessarily public. Stability and scope describe different properties of the assignment.
Identification Limits
An IP address can provide context about a connection, but its ability to identify someone is limited. A public address may correspond to a household, business, mobile network, hotspot or shared infrastructure. Address changes and NAT also prevent it from functioning as a permanent personal identifier.
Geolocation databases estimate a country, region, city or operator from registries and network observations. This approximate location is not equivalent to GPS coordinates and may be wrong, especially with mobile networks, corporate infrastructure or connections routed through other territories.
A VPN or proxy can make the destination service observe the intermediary’s public address. A firewall, by contrast, filters traffic according to rules but does not itself hide the address needed for communication. Effective privacy depends on the complete set of data and controls, not only on the IP address.
Use in Digital Services
Digital services can record IP addresses to operate networks, investigate incidents and apply controls. Each use needs to consider context, accuracy and data retention. Common functions include:
- Content delivery: Routing responses, selecting nearby infrastructure and managing availability.
- Service protection: Detecting anomalous patterns, limiting requests and supporting abuse investigations.
- Technical measurement: Analysing traffic, filtering automated activity and connecting session events with other signals.
- Geographic adaptation: Applying approximate geotargeting by territory, language or availability without assuming an exact position.
In analytics or advertising, an IP address alone does not prove that two events belong to the same person or that two addresses represent different users. Reliable measurement must account for shared or changing addresses, VPNs, proxies and applicable privacy obligations.