The spinal column is a complex structure composed of 33 individual vertebrae stacked end-over-end from the top of our necks to the bottom of our tailbone. It provides structure and support while also enabling us to move. A healthy spine has a natural S-shaped curve consisting of three natural curves — one at the neck (called the cervical spine) and another at the lower back (called the lumbar spine), both of which have a slight concave curve; and third at the middle back, with a gentle convex curvature. These natural curvatures act somewhat like a mattress coil, compressing in on themselves to absorb shock while also allowing for full range of motion.
Unfortunately, sometimes the spine can develop an abnormal curvature either in utero, as a child grows into adolescence, or as we age due to spinal degeneration. Abnormal sideways curves in the spine are called scoliosis.