JavaScript
Temporal dead zone
The span between a let/const binding entering scope and being initialised, where access throws ReferenceError.
Why interviewers ask about it
let and const are hoisted, just not initialised. The TDZ converts a silent undefined into a loud error - that is the improvement over var.
Related terms
This term is part of the free Python Full-Stack interview preparation module - browse the full glossary for every definition.