Gemini is an astrological sign, which originated from the constellation Gemini, and is the third sign of the zodiac. Gemini is classed as a Positive or masculine, extrovert sign; its element is Air and its Quality is Mutable. Traditionally in astrology Gemini is ruled by the planet Mercury.
Under the tropical zodiac, Gemini is occupied by the Sun from May 21 → June 21, and under the sidereal zodiac, it is currently from June 15 → July 15. The Taurus-Gemini Cusp dates are between May 19 → May 23. So some people who're thought to be pure Taureans, or Geminis, are not.