The Gonstead system comes from a man named Clarence Gonstead. He created the system and technique back in 1920-30 that is still being used to treat thousands of people today.
The Gonstead system consists of 5 key aspects before adjusting:
Visualizing the subluxation of the patient whether it be postural or blemishes, like zits on the spine.
Static palpation to feel for edema (swelling) or fluid build up around the vertebral spinous, dryness or sweat in the specific area, etc.
Motion palpation to feel the vertebra being in a fixed position and find the exact line of correction to adjust for a specific adjustment
Taking and analyzing X-rays to look for potential subluxations and looking at the overall health of your spine.
Using instrumentation like a nervoscope (an instrument to measure temperature difference in the spine) to help pinpoint where a subluxation is and when to/when not to adjust the spine.
The technique is done by hand, skin on skin contact to manually reposition the bone back into its proper juxtaposition those taking pressure off the nerve.