How IAsyncEnumerable<T> combines IEnumerable<T> lazy evaluation with Task asynchronous execution:

public async IAsyncEnumerable<SensorReading> StreamReadingsAsync([EnumeratorCancellation] CancellationToken ct = default)
{
    while (!ct.IsCancellationRequested)
    {
        SensorReading reading = await _sensorClient.ReadNextAsync(ct);
        yield return reading; // Yields item as soon as it arrives!
    }
}

// Consumer
await foreach (var reading in StreamReadingsAsync(cancellationToken))
{
    ProcessReading(reading);
}

Allows consuming high-volume telemetry, database cursors, or WebSocket packets chunk-by-chunk without loading entire datasets into RAM!

Always add [EnumeratorCancellation] to the CancellationToken parameter so .WithCancellation(ct) on the consumer side passes tokens to the enumerator correctly.

Entity Framework Core's .AsAsyncEnumerable() streams millions of database rows directly to HTTP responses with near-zero memory footprint.