Sciatica refers to pain that occurs along the sciatic nerve, which runs from the lower back through the hips and buttocks and down each leg. It is typically caused by compression or irritation of the nerve, often due to a herniated disc, bone spur, or spinal stenosis. The pain can range from mild to severe and may be accompanied by symptoms such as numbness, tingling, or muscle weakness in the affected leg. Sciatica usually affects only one side of the body and can worsen with certain movements, such as sitting for extended periods or standing up. Physical therapy can help provide relief.