Asyncio is a built-in Python library available from Python 3.4 onwards, used to write concurrent programmes with the async and await syntax. Unlike multithreading or multiprocessing, asyncio achieves concurrency within a single thread through an architecture known as an event loop. It is particularly well suited to I/O-bound tasks, where execution time is dominated by waiting for external responses, such as fetching data from web APIs, querying databases, or reading network streams.
How it works - cooperative multitasking
In standard sequential code, if a programme requests data from a website, the entire application blocks until the server responds.
Asyncio uses cooperative multitasking. When a task reaches a waiting point, such as an API request, it voluntarily pauses and yields control back to the event loop. The event loop then switches to another task that is ready to run. When the external response arrives, the event loop resumes the original task so that it can complete its work.
Core building blocks
