Spinal manipulation is a technique where the practitioner uses their hands to apply a controlled thrust (that is, a force of a specific magnitude or degree in a specific direction) to a joint of your spine.
Typically, you will hear a “crack” or “pop” associated with the manipulation/adjustment. The goal of the adjustment is for releasing joint restriction/fixation but may also aid to relieve pain, improve generalized stiffness in joints, relieve tension in muscles, and to improve overall mobility.