IAsyncEnumerable<T>

A Task<List<T>> forces the whole sequence to materialize before any consumer can touch it. If a server returns a million matching products page by page, the caller waits for every page to land in memory before the first item shows up. IAsyncEnumerable<T> fixes that by giving back an asynchronous stream: each item becomes available the moment it arrives, and the consumer iterates with await foreach. This lesson covers what IAsyncEnumerable<T> is, how to produce one with async iterator methods, how to consume it, and how cancellation and ConfigureAwait work on async streams.