Wat is Back-pressure, slow consumer, conflation?

Back-pressure is the propagation of a consumer’s slowness to its producer, which must wait or refuse new work when the queue between them is full. A slow consumer is a consumer whose rate is below its input’s, so that its queue grows or, on a ring that does not wait, it is lapped. Conflation is the deliberate delivery of only the latest value of each item (a price level, a quote) to a consumer that cannot take every update.