kwargs

Kwargs is a term used in Python to describe keyword arguments collected by a function. In a function definition, a parameter preceded by ** collects any keyword arguments that are not matched by other named parameters into a dictionary. The convention is to name this parameter kwargs, though the name is not required.

Inside the function, kwargs behaves like a standard dictionary. For example, given def connect(host, port=80, **kwargs): you can call connect('example.com', timeout=5, use_ssl=True). Within the function, kwargs['timeout'] yields 5, and kwargs['use_ssl'] yields True. Kwargs is also commonly used to implement flexible APIs, wrappers, or decorators, where additional options may be passed through to inner calls.

Kwargs can be used in two directions. First, to accept arbitrary keyword arguments in a function, enabling forward compatibility and extensibility. Second, to pass a dictionary of options as keyword arguments to another function using unpacking syntax, e.g., options = {'timeout': 5}; connect('example.com', **options). A function may be defined to work with both regular parameters and kwargs, and it can also be combined with *args to handle both positional and keyword arguments.

Common cautions include avoiding unexpected keys or conflicts with named parameters, and recognizing that keys in kwargs are strings representing parameter names. The conventional name kwargs is widely used, but any valid identifier can be used. Kwargs provides a lightweight mechanism for extensible interfaces and wrapper patterns without requiring explicit parameter lists for every option.