Rubber Ducking

“Rubber ducking is a reference to a story in the book The Pragmatic Programmer in which a programmer would carry around a rubber duck and debug their code by forcing themselves to explain it, line-by-line, to the duck. Many programmers have had the experience of explaining a problem to someone else, possibly even to someone who knows nothing about programming, and then hitting upon the solution in the process of explaining the problem. In describing what the code is supposed to do and observing what it actually does, any incongruity between these two becomes apparent. More generally, teaching a subject forces its evaluation from different perspectives and can provide a deeper understanding. By using an inanimate object, the programmer can try to accomplish this without having to interrupt anyone else.”
Source: https://en.wikipedia.org/wiki/Rubber_duck_debugging