What are Python lambda functions and when would you use them?

A Python lambda function is an anonymous, one‑line function defined with the lambda keyword. It takes any number of arguments but can contain only a single expression, whose result is returned automatically. Lambdas are useful for short, throw‑away functions that are passed to higher‑order functions like map, filter, or sorted, or as simple callbacks. For example, sorted(list_of_tuples, key=lambda x: x[1]) sorts by the second element. Lambdas improve readability when the function logic is trivial and avoids the overhead of defining a full named function. However, for more complex logic, multi‑line operations, or when debugging, a regular def function is clearer. Lambdas are also limited to a single expression, so they cannot contain statements, loops, or multiple return statements.