foo

Foo is a metasyntactic variable used as a placeholder name in computer programming, documentation, and technical examples. It is commonly paired with bar and sometimes baz to illustrate code structure, algorithms, and data types without relying on domain-specific identifiers. In programming, foo serves as a generic identifier for values, functions, or modules in sample code across languages such as C, Python, JavaScript, and Java.

Beyond programming, foo appears in instructional texts, test data, and design documents as a placeholder to avoid implying particular content. The set of metasyntactic tokens, often extended with bar, baz, qux, and others, provides convenient stand-ins in explanations and tutorials.

Origin and history: The exact origin of foo is uncertain. The tokens gained popularity in mid-20th-century computing culture, appearing in manuals, textbooks, and code samples. They are thought to have arisen as nonsensical placeholders that allowed writers to demonstrate syntax and structure without meaningful naming. The specific pairings with bar and baz became conventional in documentation and teaching materials.

Impact and usage: Today, foo remains entrenched in programming culture as a universal placeholder. It appears in software documentation, open-source examples, coding tutorials, and educational resources, serving to illustrate concepts without asserting concrete semantics. While its meaning is context-dependent, the use of foo and related tokens is widely understood among programmers.