Recursion is the process of defining a problem (or the solution to a problem) in terms of (a simpler version of) itself. For example, we can define the operation "find your way home" as: If you are at home, stop moving.

In computer science, recursion is a method of solving a computational problem where the solution depends on solutions to smaller instances of the same problem. Recursion solves such recursive problems by using functions that call themselves from within their own code.

This can be understood in terms of a recursive definition of a syntactic category, such as a sentence. A sentence can have a structure in which what follows the verb is another sentence: Dorothy thinks witches are dangerous, in which the sentence witches are dangerous occurs in the larger one.

It means to look for something until you can look no further. So a recursive lookup of CDP neighbours would be to look at at Device A, to see its connected to Device B. Then look at Device B to find that's connected to Device C, and so on until you find what you are looking for.