Although most people seem to be on the right track, there still appears to be a bit of confusion. There are not
six senses, or ten as someone suggested, but, in fact, there remains only five. The five are as follows:
vision,
gustation (taste),
olfaction (smell),
auditory (hearing) and
somatosensation. It is the last one, somatosensation, which is causing the confusion. All the extra senses that people are adding are somatosensory in origin. Somatosensation literally means "
body-sense"; it is the set of senses which originates from the entire body, including skin, bone, muscle and
tendon, not limited to the specialised sensory organs of the
head.
Somatosensation can be broken down into proprioception, kinethesis and the cutaneous senses, which include temperature, tactile(touch) and pain. The reason why all these seemingly different senses are collectively known as somatosensation isn't just because they are all body senses, but has more to do with the structure of the brain. Different areas of the brain are associated with different functions. The area related to vision is separate in structure and function to that of hearing, and they are both separate from somatosensation. However, the area responsible for somatosensation, the somatosensory cortex, receives input from structures responsible for pain, touch, proprioception, etc. Consequently, these senses may appear to be separate entities at first glance but it is their common destination, and subsequent similarity in processing, that has combined them into a whole.