What is the difference between hot and cold data streams in the context of systems and applications?

Hot streams of data are streams that start generating data immediately after creation, regardless of whether there are subscribers. They are constantly active and can drop data if the subscriber cannot process it in time.

Cold streams of data start generating data only when there is a subscriber. Each subscriber receives the full data stream from the beginning, which is convenient for replay or delayed processing.

Example: in Android, a hot stream can be SharedFlow, and a cold stream can be a regular Flow.