How many vertebrae are in a persons backbone?

An adult human typically has 33 vertebrae in their backbone, which are divided into five regions: cervical (7), thoracic (12), lumbar (5), sacral (5, fused), and coccygeal (4, fused). However, the number may vary slightly due to individual anatomical differences. In infants, there are more individual vertebrae, as some have not yet fused.