In astronomy, a Retrograde is when a planet is observed from Earth as moving in a backwards motion through the Zodiac. What is actually happening is the Earth's orbit around the Sun is over taking the orbit of another planet in our solar system, like that of Mercury, therefore it appears that the planet is moving backwards, when actually it is just an illusion.
In astrology, the planet Mercury represents communication, mentality, and common sense. Mercury rules the signs Gemini and Virgo. The astrologist's characteristic of a retrograde when seen in a Natal chart or transits is a capital 'R', subscript to the right of the planet.
A Mercury Retrograde can either be an exciting time for one who has a natal Mercury Retrograde, or can be quite confusing for those who are Mercury direct, or born at the time of a non-retrograde. Those of Mercury direct can get the negative affects of this planet, and may find themselves in mental confusion, missing appointments, personal misunderstandings, delayed or disrupted communications, and also problems or glitches with technology, computers, cars, cell phones, or any electrical communicative tool.
Those born during a Mercury Retrograde (signified by the capital 'R' subscript to the right of Mercury on their Natal (birth) chart) may find that they are "in their true sign" during this time. Being at the peak of their wits, strong in communication, and on top of things. They will carry a more natural flare, but are still susceptible to the advertise affect, especially with communication technology, though not to the extreme as those who are born with Mercury direct (non-retrograde in your natal chart).
Though not everyone feels the extremes, caution is still raised for any communication interactions or mental activity. Also, it is recommended to avoid signing any legal documents or closing important deals or agreements during a Mercury Retrograde.
Some individuals are more sensitive then others, and feel the retrograde approaching before it actually begins. The current Mercury Retrograde is from Thursday, January 2nd, 2003 and lasts twenty days until January 22/23, 2003.
Love and Light,