A subluxation is simply when a bone, usually a spinal bone, is out of place but not completely dislocated.
It’s actually a medical term that means a joint is misaligned but not entirely (which would be a ‘luxation’).
In the spine a subluxation can cause pressure to be put onto the delicate spinal nerves located there and this pressure can cause ill health and disease because of the interference that it causes in the communication between the brain and the body.
Chiropractors, with their hands and also other tools, use light, specific force to put the subluxated bones back into place. With time this will allow the body to heal itself as the nerves recover.