Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Rapids are hydrological features between a run (a smoothly flowing part of a stream) and a cascade. Rapids are characterised by the river becoming shallower with some rocks exposed above the flow surface. As flowing water splashes over and around the rocks, air bubbles become mixed in with it and portions of the surface acquire a white colour, forming what is called "whitewater". Rapids occur where the bed material is highly resistant to the erosive power of the stream in comparison with the bed downstream of the rapids. Very young streams flowing across solid rock may be rapids for much of their length.

Rapids! were an indie rock band from Bournemouth, England, which formed in August 2009.

The Real-Time Automated Personnel Identification System (RAPIDS) is a United States Department of Defense (DoD) system used to issue the definitive credential within DoD. RAPIDS uses information stored in the DoD Defense Enrollment and Eligibility Reporting System (DEERS) when providing these credentials. Used together, these two systems are commonly referred to as a DEERS/RAPIDS system or DEERS/RAPIDS infrastructure.