Recursive call may appear difficult when you initially approach, but it cannot be overlooked when it comes to studying algorithms. It bears a close connection with mathematical induction, and those who once had a frustrating experience with mathematical induction in the past may feel intimidated, but there is nothing to fear. It is my opinion that anyone who understands grammatically correct your native language and knows how to count natural numbers can master the use of recursive calls. In this chapter, we will attempt to understand recursive calls and their correct usage by considering two themes: the “Hanoi tower” and “Fibonacci numbers.”