The general categories of pain are acute pain, chronic pain, and intermittent or recurrent pain.  Acute pain is defined as pain that generally lasts less than one month.  Acute pain can often be attributed to a specific injury or area of tissue damage.  This is the type of pain that you would experience when you suffer back strain/sprain, fracture bone, or a cut finger.  Chronic pain is generally defined as pain that lasts more than three to six months.  This is generally the pain that remains after the tissue has healed.  Chronic pain may occur secondary to the way tissue healed or to the degree of scar tissue that may have formed.  Chronic pain can also occur as the result of changes which take place in the spinal cord and brain, referred to as pain of central origin.  The termed intermittent or recurrent pain is actually the subcategory of acute pain.  This refers to acute pain, which occurs time and time again.  A good example of recurrent acute pain is local back pain associated with inflammation, which comes and goes.   

Pain can be described as focal, diffuse, or radiating in nature.  Focal pain refers to pain within a small area, whereas diffuse pain refers to pain which migrates away from a focal region resulting in a larger and relatively symmetric distribution.  The term radiating pain refers to pain which extends from a focal point of origin in a specific direction.  Sciatic pain is a type of radiating pain associated with compression of the lumbosacral nerve roots, usually from disc herniation. This pain may be described as electric jolts in the back of the thigh and leg or a deep constant ache in the posterior thigh and leg.