Mercury, the closest planet to the Sun hurtles through space faster than any other planet in the Solar System. Mercury takes a mere 88 days to revolve around the sun

This is indicative of its active, speedy and ever changing principle inherent in its affect in our Astrological Charts and day to day lives. 

Communication is the theme of this planet. Communication can come in many different forms, verbal, written, contractual, etc… In Greek mythology, Mercury was personified by god Hermes "The Messenger of The Gods”. And like Hermes, Mercury is the area of our lives where communication is emphasized. This communication can be verbal or mental, with others or with one’s self.

Mercury also, rules short distance travel i.e. cars, buses, trains, flights (domestic). It’s rulership also extends to transport of the blood through the vessels in the body, synaptic fires in the brain, and signals sent through the nervous system.