Number (identifier)

A sequence of digits or symbols assigned to identify, locate, or contact a person, place, device, or account. Unlike a quantity, it functions as a label.

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Telephone number: A digit sequence used to route calls or messages to a telephone service or subscriber. It is the clearest example of a number used to contact someone.
Positional notation: A numeral system in which a symbol's value depends on its position. Many identifiers use positional digit strings, though their digits need not represent a quantity.
Natural number: A member of the counting-number system, commonly including zero or beginning at one depending on convention. An identifier may look like a natural number but does not express a count.
Personally identifiable information: Information that identifies or can reasonably be linked to a particular person. A persistent personal identifier can expose identity when linked with other records.
Internet Protocol address: A numerical label assigned to a device or network interface for communication using Internet Protocol. It identifies network destinations so data can be routed to them.
Decimal numeral system: A base-ten positional numeral system using the digits 0 through 9. Telephone and account identifiers commonly use decimal digits.
Nominal scale: A measurement scale that assigns labels to categories without implying order or distance. Identifiers often function as nominal labels rather than measurable values.
Data matching: The process of linking records from separate datasets that describe the same entities. Shared identifiers make record linkage easier, including across databases.
Vehicle registration plate: A plate displaying a registration identifier assigned to a road vehicle. Its displayed characters identify a vehicle within a registration system.
Alphanumeric: A character set or string containing both letters and numerals. Many identification schemes extend beyond digits to reduce ambiguity or increase capacity.