Explain Recursion to a Non-CS Audience

The engineering-specific closer of the Goldman Hirevue. Explain recursion to someone with no CS background — what it is, why one might use it, and an everyday analogy. Requirements 30 seconds of prep, 2 minutes to answer. Audience: explicitly non-technical. No code, no jargon. The grading axis is communication clarity, not technical accuracy of the bytecode. A close variant of the same question replaces "recursion" with "regression" (the statistical concept), and uses the same grading criteria. Notes A strong answer hits three beats in 90 seconds: What it is — a method that calls itself with a smaller version of the same problem, with a base case to stop. Why use it — when a problem naturally decomposes into a smaller copy of itself (Russian nesting dolls, family-tree traversal, folder-inside-folder). A concrete analogy — looking up a word in a dictionary that says "see another word"; reading a book that says "see chapter 3" which says "see chapter 5"; finding the last person in a line by tapping the person in front of you to ask the same question. Avoid: "call stack," "frame," "tail-call optimization," pseudocode, Fibonacci. These signal you're talking past a non-technical audience. Avoid: leading with the dictionary definition ("recursion is a function that calls itself"). The analogy comes first; the definition lands after. Preparation Write out three analogies and rehearse them with a non-engineer in the room. Their feedback is the most useful signal you can get. Have a second 90-second answer ready for "explain regression to someone without a CS background" — same template, different topic. 30 seconds of prep is not enough to construct an analogy; have one already loaded before the question even appears.