In computer programming, an anonymous function (also function literal or lambda abstraction) is a function definition that is not bound to an identifier. Anonymous functions are often:

1. arguments being passed to higher-order functions, or
2. used for constructing the result of a higher-order function that needs to return a function.

If the function is only used once, or a limited number of times, an anonymous function may be syntactically lighter than using a named function. Anonymous functions are ubiquitous in functional programming languages and other languages with first-class functions, where they fulfill the same role for the function type as literals do for other data types.