Degenerative disease may lead to spinal canal stenosis and long-lasting pain. It is among the leading cause of disability that may affect the ability to work. It has become more common in an increasingly aging population. MRI is the most comprehensive imaging modality and provides detailed morphologic information. A standardized terminology facilitates communication with referring physicians. Yet imaging findings need careful interpretation in conjunction with the results of clinical tests and symptoms to truly help guide therapeutic decision making. This review summarizes aspects of normal anatomy of the intervertebral disk, pathologic mechanisms, terminology, and examples of the imaging spectrum of disk degeneration and herniation.