It is the primary technique for crossing synchronisation boundaries.
Interestingly when someone pointed out that slaves occasionally mutinied that aligned the metaphor with greater precision because occasionally the data changes exactly on a clock edge and the flip flop cannot decide which state to adopt in which case it sometimes oscillates for an indeterminate time with catastrophic consequences for the logic. Flip-flop metastability is mitigated by some techniques such as multiple ranking.
The historic term is master-slave, and whilst I condemn this behaviour in humans, it is an accurate metaphor for this electronic construct and the electronics is not offended by this required behaviour.
Stewart
