Virgo

Virgo (♍) is the sixth astrological sign in the Zodiac, originating from the constellation of Virgo. In western astrology, the sign is no longer aligned with the constellation as a result of the precession of the equinoxes. In astrology, Virgo is considered a "feminine", negative (introvert) sign. It is also considered an earth sign and is one of four mutable signs. Virgo is traditionally ruled by the planet Mercury, but Ceres and several other planets have been suggested as the ruler of Virgo by some modern astrologers. Being the sixth sign of the zodiac, Virgo has been associated with the astrological sixth house.
Individuals born when the Sun was in this sign are considered Virgo individuals. Under the tropical zodiac, the Sun is in Virgo roughly from August 23 to September 22, leaving it at the moment of autumnal equinox, by definition. Under the sidereal zodiac, it is currently there roughly from September 17 to October 17. The Sanskrit name of Virgo in Hindu astrology is Kanyā (Girl).

Compatibilities
Based on Elements within the Zodiac, Virgo is considered compatible with Taurus, Capricorn, and Virgo itself.
There are many variables that determine compatibility in astrology, such as birth dates, birth months, birth years, position of a sign within the Sun, the Moon, Stars, etc. The signs listed as compatible with Virgo do not reflect an individual profile or individual reading as interpreted within astrology, but rather reflect a general guideline and reference to compatibility as dictated by variables such as Qualities and Elements within the Zodiac. The branch of astrology dealing with non-interpersonal compatibilities is called Synastry.
source : http://en.wikipedia.org/wiki/Virgo

What is Synastry

Astrological compatibility (synastry) is the branch of astrology that studies relationships by comparing natal horoscopes. A natal horoscope is a chart, map, or imaginary snapshot of the planets in the Solar System and their positions in the zodiac at the exact time of a person's birth. The signs of the Zodiac represent 12 different types of spiritual energy and purpose. The planets in the Solar System are associated with at least one, but most often two signs of the zodiac.

Relationships between planets, signs (types of energy), and houses (sectors of the chart) are described in words and /or often rated in numbers to show to what degree, how, and in what ways one person is compatible or incompatible with another. The assessment is based on the patterns and distributions of energy in the respective and combined charts.

Compatibility between Zodiac signs is always approached within a particular branch of astrological tradition: Chinese astrology, Western astrology or Vedic astrology.
Source : http://en.wikipedia.org/wiki/Synastry