Ankylosing spondylitis causes early morning stiffness, poor posture, and fatigue due to inflammation of the spine and sacroiliac joints. It is more common in males under 40 and those with a family history. Diagnosis involves x-rays showing fusion of the spine, MRIs revealing inflammation, and blood tests for the HLA-B27 gene and elevated ESR. Treatment focuses on exercise, posture, stretching, heat/cold therapy, massage, not smoking, and medications like NSAIDs or surgery for severe cases.