In Python, single and double asterisk (* and **) SYMBOLS are defined as multiplication and exponentiation operators respectively. However, when prefixed to a variable, these symbols carry a special meaning. Let us see what that means.

A Python function is defined to receive a certain number of arguments. Naturally the same number of arguments must be provided while calling the function, otherwise Python interpreter raises TypeError as shown below.

This is where the use of formal argument prefixed with single * comes. In a function definition, an argument prefixed with * is able to receive variable number of VALUES from the calling environment and stores the values in a tuple object.

Python allows a function to be called by using the formal arguments as keywords. In such a CASE, the order of argument definition need not be followed.

However, if you want to define a function which should be able to receive variable number of keyword arguments, the argument is prefixed by ** and it stores the keyword: values passed as a dictionary.

In fact, a function can have positional arguments, variable number of arguments, keyword arguments with defaults and variable number of keyword arguments. In order to use both variable arguments and variable keyword arguments, **variable should appear last in the argument list.