Although spinal curvature (or curvature of spine) can refer to the normal concave and convex curvature of the spine, in clinical contexts, the phrase usually refers to deviations from the expected curvature, even when that difference is a reduction in curvature.

Types include kyphosis

Kyphosis

Kyphosis , also called roundback or Kelso's hunchback, is a condition of over-curvature of the thoracic vertebrae...

, lordosis

Lordosis

Lordosis is a medical term used to describe an inward curvature of a portion of the lumbar and cervical vertebral column. Two segments of the vertebral column, namely cervical and lumbar, are normally lordotic, that is, they are set in a curve that has its convexity anteriorly and concavity...

, and scoliosis

Scoliosis

Scoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...

.

The thoracic and sacral (pelvic) curves develop in the fetus. Around 6 months after birth the cervical curve appears which helps hold the head up. Around one year of age the lumbar curve develops which helps with balance and walking. The cervical and lumbar curves are considered secondary curves whereas the thoracic and sacral curves are primary.