The spinal disc is a soft cushion that sits between each vertabrae of the spine. The spinal discs are composed of a tough outer cartilage (annulus fibrosus) with a squishy center (nucleus pulposis). Like a shock absorber for a car, the disc is the shock absorber for the spine. When too much pressure is placed on the disc, it bulges or herniates. Think of it like a jelly doughnut. Squeeze it too hard and the jelly comes out. That is called a Herniated Disc (Slipped Disc, Bulging Disc).