FrontendHaltReact·Advanced·Conceptual·1 min read
What is Fiber?
Short interview answer
Fiber is React's internal unit-of-work representation and reconciliation architecture. It lets React split, prioritize, pause, resume, and discard render work before commit. The important interview distinction is that render work may be interruptible while commit work applies a consistent result.
Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.