This is a process that Chiropractors use to relieve pain and add motion to the spine. The adjustment is performed by the Chiropractor placing their hands on your body and finding where you may be tender or not moving well. They then will use a high-velocity low amplitude thrust. This is a very safe and pain-free procedure.
The chiropractic adjustment helps decrease pain by stimulating your mechanoreceptors. It's almost as if you hit your thumb with a hammer and started shaking your thumb. That shaking decreases the pain signals.
It also rapidly stretches the tiny muscles in your spine like the rotatores and multifidus. This rapid stretching helps to re-activate the muscle and strengthen your spine.