Streaming and Backpressure

When data is too big to fit in memory or arrives continuously, you process it as a stream, one piece at a time, with bounded memory, rather than loading it all. Backpressure is the mechanism that stops a fast producer from overwhelming a slow consumer, by signaling 'slow down' rather than buffering unboundedly until you run out of memory. Applied-AI interviews probe it because AI pipelines process huge datasets and token streams, and the naive load-everything approach OOMs while unbounded buffering crashes under load.