Recursion is one of those things that some of you may or may not have heard of / attempted. This section of the notes will introduce to you what it is if you do not already know and how it works. Some of this will be review some will not. Take your time to try and understand this process.
It is important to know at least a little recursion because some algorithms are most easily written recursively. The text book sometimes only provide the recursive version of an algorithm so in order for you to understand it, you will need to understand how recursion works.