Start with a one-line definition, explain why it matters, give a concrete example, compare to alternatives where useful, acknowledge edge cases, and use simple language with defined jargon. Clarity is a skill interviewers assess.

Because it anchors the explanation before you go deeper. 'A closure is a function that remembers its lexical scope' gives the interviewer a clear starting point, so the rest of your explanation builds on a shared understanding.

Because a small code example makes the concept click in a way abstract descriptions cannot. For closures, write a counter factory function. For the event loop, show setTimeout 0 vs a promise. Examples beat descriptions.