# Async iteration and generators

In web-programming, we often need to work with fragmented data that comes piece-by-piece.

That happens when we upload or download a file. Or we need to fetch paginated data.


For
Either we need to download or upload something, or we need

In the previous chapter we saw how `async/await` allows to write asynchronous code.

But they don't solve



Regular iterators work fine with the data that doesn't take time to generate.

A `for..of` loop assumes that we