Be clear about the trade-off: "asyncio shines for I/O-heavy services like API gateways handling thousands of concurrent requests. For CPU-bound work or simple scripts, it adds complexity without benefit."
asyncio uses cooperative multitasking: a single thread runs an event loop that switches between coroutines at await points. Best for I/O-bound workloads with many concurrent connections (web servers, API clients, database queries). Differs from threading: no GIL overhead, no race conditions from shared mutable state, but all code must be non-blocking — one CPU-bound coroutine blocks everything. Strong candidates discuss when asyncio is overkill, how to integrate sync and async code (run_in_executor), and popular async frameworks (FastAPI, aiohttp).
Tests understanding of Python concurrency models. Candidates who cannot explain the event loop or confuse async with threading will write incorrect concurrent code. Ask about a real project where they chose async (or chose not to).