How does asynchronous execution differ from synchronous, and in which cases is each preferable?

In synchronous mode, task execution occurs sequentially: one task must be completed before the next begins. This is simple and clear, but if a task blocks execution (for example, waiting for a network response or reading a file), the entire process stops.

Asynchronous mode allows tasks to be started without waiting for their completion, and to continue working. This is especially effective for input/output operations, where the main thread can be unblocked to handle other tasks.

When to use:

• Synchronous mode is suitable for simple, quick operations or when the order of execution is critical.
• Asynchronous mode is used for network requests, file operations, databases, where delays are expected, to improve performance and responsiveness.

Example in Python using asyncio:

import asyncio

async def say_after(delay, what):
    await asyncio.sleep(delay)
    print(what)

async def main():
    await asyncio.gather(
        say_after(1, 'hello'),
        say_after(2, 'world')
    )

asyncio.run(main())