Sometimes, pain is hard to describe. In fact, it can present differently for each person, which is why people perceive and tolerate pain in different ways. The ability to cope with pain differs markedly from person to person. Some people can tolerate severe pain without complaint, where others react strongly to it (by crying or complaining) even though the pain may not be intense. This is why, in most cases, the reaction to pain is not always a reliable indicator of its real intensity.

Besides the discomfort it causes, pain also plays an important role as an internal alarm. It warns us that something in the body is not working well and calls for immediate attention, as when pain is acute and takes place for brief periods. In some recurrent diseases, pain can be chronic in nature, developing and persisting over a longer period of time. In these conditions, pain is not primarily an alarm signal, but one of a number of symptoms that accompany the disease. Chronic pain can seriously diminish a person's quality of life.