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Recursion is a programming concept where a function calls itself in its own definition. In Python, a recursive function is a function that, in order to accomplish its task, makes one or more calls to itself with modified arguments. The process of a function calling itself is known as a recursive call. 

An example of recursive functions in Python is to calculate the factorial of a number (code):

   Output:

120 

In the example above, the factorial function calculates the factorial of a number n by recursively calling itself with a modified argument (n - 1). The base case (if n == 0 or n == 1) is crucial to prevent the recursion from continuing indefinitely and causing a stack overflow. In this case, when n is 0 or 1, the function returns 1, serving as the termination condition. 

Recursion can be a powerful and elegant technique, but it's important to use it judiciously and ensure that the base case(s) are well-defined to avoid infinite recursion. Improperly handled recursion can lead to a stack overflow error. 

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