Your spinal column is remarkable because it is both quite flexible and very strong.
Did you know that you have 7 vertebrae in your neck to hold up your head? The 12 below have adjacent ribs and the 5 lumbar vertebrae below these sit on your pelvis and make up your low back.
You have 24 vertebrae sitting on top of your pelvis with complex articulation between each vertebra involving movement in three planes, axial rotation plus compression and extension. This requires complex organisation between your brain and the receptors in joints, ligaments, tendons and muscles to maintain normal patterns of movement. Your body is very adaptable. If a joint in your back decides that it doesn't want to move in a particular direction, another joint above or below will move for it instead. YOU WONT KNOW THAT AN ADAPTION HAS OCCURRED because its unlikely to hurt, but your spine has created an abnormal or adapted pattern of motion that is likely to persist. Chiropractors are trained to find and correct abnormal patterns of spinal motion to restore normal healthy function.
And, in the same way as you have your car or teeth checked, it is a healthy move to have your spine checked periodically to ensure your spine's health.