Q.A sideways (lateral) curvature of the spine, giving it a 'C' or 'S' shape when seen from behind, is called:

Imagine your spine as a column of building blocks — the vertebrae — stacked one on top of the other. From the side, a healthy spine is not a straight rod; it has gentle, natural curves that act like springs, absorbing shock and keeping your head balanced over your pelvis. Now picture those curves becoming exaggerated, or the spine twisting sideways. That is the core idea behind spinal curvature disorders: the spine loses its healthy alignment, and the change is significant enough to cause problems.

The three main types are scoliosis, kyphosis, and lordosis. Each describes a different direction of abnormal curve.

Scoliosis is a sideways curve — the spine bends to the left or right, often forming an 'S' or 'C' shape when viewed from behind. It is the most common curvature disorder and usually appears during the growth spurt just before puberty. In many cases, the cause is unknown (doctors call this idiopathic scoliosis). The key point is that a small sideways curve is normal; scoliosis is diagnosed only when the curve is pronounced enough to risk twisting the rib cage or affecting posture.

Kyphosis is an exaggerated forward rounding of the upper back. Everyone has a natural curve there, but when it becomes too sharp — think of a hunchback posture — it is called kyphosis. It can result from poor posture over years (postural kyphosis, which is flexible and correctable) or from structural problems in the vertebrae themselves (Scheuermann's disease, which is rigid and more serious).

Lordosis is an excessive inward curve of the lower back. A small inward curve is normal, but when it becomes too deep, the abdomen may stick out and the buttocks appear more prominent. This is sometimes called swayback. It can be caused by obesity, weak core muscles, or conditions that affect the hip joints. …