Identificador

Identificador is a term used to refer to a name, code, or value that uniquely identifies an element within a set or system. It is widely applied in computing, databases, networks, and information management, as well as in linguistics and data modeling.

In programming languages, an identifier is a sequence that names variables, functions, types, labels, and other entities. Rules for identifiers vary by language, but common restrictions include: they must start with a letter or underscore, may contain letters, digits, and underscores, must not include spaces, and must not be a reserved keyword. Identifiers are often case-sensitive. They provide a human-readable alias to a memory location or resource and are subject to scope and lifetime.

In databases, an identifier may refer to a primary key or a surrogate key that uniquely identifies a row in a table. It can be a single column or a composite key. It must be unique and often not null. Identifiers enable relationships via foreign keys.

Globally and universally unique identifiers, such as UUIDs and GUIDs, along with IRIs and URNs, are used to achieve unique identification across systems and time. They support data exchange, synchronization, and distributed architectures.

In data models and software architecture, identifiers help reference entities, track provenance, and support indexing and lookup. Designers consider natural keys versus surrogate keys, weighing readability against stability and performance.

Security and privacy considerations note that identifiers should be designed to avoid leaking sensitive information. When appropriate, opaque tokens or pseudonymous identifiers can protect privacy while preserving linkability and functionality.

Standards and language specifications define formal rules for identifiers; for example, SQL uses delimited identifiers, and many programming languages specify their own lexical grammar for what constitutes a valid identifier.