identifer

An identifier is a name used to identify a distinct entity in a program, data model, or information system. In programming languages, identifiers name variables, functions, types, labels, and other entities. Note that "identifier" is the standard spelling; "identifer" is a common misspelling.

Rules and syntax: Most languages restrict identifiers to letters, digits, and underscores; they cannot begin with a digit. Case sensitivity varies between languages, and many reserve certain words that cannot be used as identifiers. Identifiers should be human-readable and descriptive, such as totalSum or userIndex.

Binding and scope: An identifier has a binding to storage or a semantic entity. The scope (global, local, block) affects visibility and lifetime. Compilers or interpreters use a symbol table to map identifiers to their declarations, types, and memory addresses. Re-declaration, shadowing, or overloading can influence how an identifier behaves in different regions of code.

Other uses: In databases, identifiers uniquely identify records (for example, primary keys). In data interchange and metadata, identifiers such as URIs or DOIs serve as stable references to entities. Across domains, identifiers enable unambiguous reference and retrieval.

Best practices: Choose clear, conventional names that reflect the entity’s role. Follow language-specific naming conventions (for example, camelCase or snake_case). Avoid reserved words and overly long names; keep identifiers consistent within a project to improve readability and maintainability.