Python's built-in async/await framework for writing concurrent, single-threaded I/O-bound code — the foundation for modern async Python web frameworks (FastAPI, Starlette, Sanic).
asyncio gives Python true async I/O via the event loop pattern: coroutines (async def) yield control on I/O operations (await) instead of blocking. The event loop multiplexes thousands of in-flight operations on one thread. asyncio is the right tool for I/O-bound workloads (API calls, database queries, file I/O), but NOT for CPU-bound work — for CPU-bound code, use multiprocessing or external workers.
Rewriting a serial 100-URL fetcher (60 seconds) as an asyncio.gather of httpx calls (3 seconds) by parallelizing the I/O.
asyncio is the foundation of high-throughput Python services — any I/O-heavy workload (API gateways, data ingestion, web scraping) belongs on asyncio.
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