Spondylitis is an inflammation of the vertebra. It is a form of spondylopathy. In many cases spondylitis involves one or more vertebral joints as well, which itself is called spondylarthritis.

Spondylitis is one of the most common causes of back and neck pain, and results from inflammation of the vertebral joints. The condition is often not detected until it has fully developed and is causing pain. The pain is usually concentrated around the cervical region of the neck, shoulder and lower spine, with downward-moving stinging pain.

Pott's disease is a tuberculous disease of the vertebrae marked by stiffness of the vertebral column, pain on motion, tenderness on pressure, prominence of certain vertebral spines, and occasionally abdominal pain, abscess formation, and paralysis.

Ankylosing spondylitis is an inflammatory disease involving the spine and sacroiliac joints, and is therefore also a form of spondylarthritis.

More Info: en.wikipedia.org