HUG
.a form of physical intimacy.
.closing or holding the arms around another person or a group of person.
.human signs of LOVE & AFFECTION.
.sometimes a romantic exchange.
.sometimes a sign of SUPPORT & COMFORT.
.sometimes a demonstration of affection and warmth.
.sometimes arising out of joy or happiness at meeting someone.
.increase levels of oxytocins (a.k.a the cuddle hormone).
.decrease blood pressure.
.dogs or other canines do not enjoy hugs as much, they interpret putting a limb over another animal as a dominance signal.
source: http://en.wikipedia.org/wiki/Hug