The human spine normally contains 33 vertebrae, including the fused vertebrae of the sacrum and coccyx.
These are arranged as 7 cervical vertebrae in the neck, 12 thoracic vertebrae in the chest, and 5 lumbar vertebrae in the lower back. Below them are 5 sacral vertebrae, which fuse to form the sacrum, followed usually by 4 coccygeal vertebrae that form the tailbone.
People sometimes answer 26 because the adult vertebral column is often described as having 26 bones: the sacral and coccygeal vertebrae have fused into larger structures. That count refers to bones, not the individual vertebrae that make up the column. In a standard anatomy or trivia question asking for vertebrae, 33 is the accepted answer.
The number is not absolutely identical in every person. Rare anatomical variations can produce totals from about 32 to 35, especially because the coccygeal region may contain three to five vertebrae. The spine also surrounds and protects the spinal cord while supporting the body and enabling movement.