A herniated or slipped disk is most often the result of natural, age-related wear and tear on the spine.
This process is called disk degeneration. In children and young adults, disks have high water content. As people age, the water content in the disks decreases and the disks become less flexible. The disks begin to shrink and the spaces between the vertebrae get narrower. This normal ageing process makes the disks more prone to herniation.
A traumatic event, such as a fall, can also cause a herniated disk.