Spinal tracts are bundles of nerve fibers located within the spinal cord that transmit signals between the brain and the rest of the body. They are organized into ascending tracts, which carry sensory information to the brain, and descending tracts, which send motor commands from the brain to the muscles. These tracts are crucial for coordinating movement and processing sensory information. For example, the corticospinal tract is a major descending tract involved in voluntary movement, while the spinothalamic tract is an ascending tract that conveys pain and temperature sensations.