In clinical practice, medical professionals need terminology for normal and pathologic conditions of the lumbar intervertebral disc. A joint effort by the North American Spine Society, the American Society of Spinal Radiology, and the American Society of Neuroradiology, through the formation of a joint task force committee, issued the Definition and Classification of Lumbar Disc Pathology (First Edition) in 2001, which has guided radiologists, clinicians, and interested members of the public for more than 10 years. Today, our understanding of the lumbar intervertebral disc has evolved, and there is an urgent need to revise and update the 2001 definition and classification of lumbar intervertebral disc pathology. As a result, the North American Spine Society, the American Society of Spinal Radiology, and the American Society of Neuroradiology have updated the first edition and completed the second edition. The second edition retains the style and most of the language of the original first edition document, with revisions to the clinical and imaging sections corresponding to the current, article published simultaneously in Spine and Spine J in December 2014 by the Joint Task Committee. Members of the Joint Committee revised the first edition of 2001 by searching pubmed for relevant literature on lumbar discs since 2001 and jointly reviewing it. The first edition was reviewed by the boards of directors of the North American Spine Society, the American Society of Spinal Radiology, and the American Society of Neuroradiology, and revised for publication. Recommended Diagnostic Classification The diagnostic classification is based on pathology. Lumbar intervertebral discs can be classified as one or more of the following pathologies: normal; congenital/developmental variant; degeneration; trauma; infection/inflammation; tumor; and/or nonsignificant morphologic abnormality. In degeneration, a fibrous ring cleft replaces the fibrous ring rupture in the first version. Picture modifications. 2. Refinement of the definitions of acute and chronic disc herniation. Modification of the distinction between herniated disc and asymmetric disc bulge; deletion of the table in the first edition. The main definitions are explained below with pictures. Figure 1 Normal lumbar intervertebral disc. (A) axial; (B) sagittal; (C) coronal. In the figure, the normal intervertebral disc consists of a central nucleus pulposus and a peripheral annulus fibrosus, completely within the boundary of the intervertebral space, proximally and distally encased by the endplates, and peripherally within the outer edge of the vertebral bulge, with no osteophytes. Figure 2 Fibrous annulus cleft. Fibrous annulus clefts can be radial (R), transverse (T), and circumferential (C), splitting the fibers of the annulus fibrosus. The transverse fissure in the figure is fully developed and perpendicular to the radial fissure, and the transverse fissure is often used to describe the splitting of extensibility limited to the peripheral annulus fibrosus and bony attachment points. Figure 3 Bulging discs. A, Normal discs, all within the boundaries shown by the dotted line; B, Symmetric disc bulge, symmetric bulging of the annulus fibrosus with less than 3 mm of the disc boundary; C, Asymmetric disc bulge, asymmetric bulging of the annulus fibrosus with greater than 25% of the disc margin. Figure 4 Herniated disc: protrusion. Axial A and sagittal B show that the disc protrusion is less than 25% of the disc and that the maximum measurement of the protrusion is less than the base of the displaced disc origin in any plane. Figure 5 Herniated disc: extrusion. Axial A and sagittal B show the same planes, with the displaced disc measuring larger than the base of its origin. Figure 6 Herniated disc: free. Axial A and sagittal B show the free disc as a prolapsed disc without any connection to the source disc. Figure 7 Herniated disc (Schmoe’s nodule). The disc material has broken through the cartilaginous endplates and protruded into the vertebral body, as shown in the sagittal view of the figure. Fig. 8 Imaging criteria for disc degeneration.A Deformed spondylolisthesis, demonstrating bony protrusions with preserved intervertebral space.B Intervertebral bone chondralization, characterized by narrowing of the intervertebral space, heavy fissures, and erosion of the cartilaginous endplates. Figure 9 Intervertebral disc integrity. Radiolucent fissures are categorized as grades 0-5 as shown on discography CT. Fig. 10 Reactive vertebral bone marrow changes. the signal changes of the vertebral bone marrow around the intervertebral disc on MRI are classified into Modic type I (A), II (B) and III (C) according to the changes in the T1 and T2 phases.