Gemini is the third astrological sign in the Zodiac and it originates from the constellation of Gemini. The sign is said to be a masculine, extroverted air sign, ruled by the planet Mercury. Individuals born between May 21st and June 21st are said to born under the sign of Gemini. Those individuals are also said to be adaptable, communicative, charming, vain, critical, fickle, insensitive, out-going and adventurous.
In Greek mythology, Gemini is associated with the brothers Castor and Pollux, twin brothers. The brothers have the same mother but different fathers, which made Pollux immortal but Castor mortal. When Castor died, it meant he would have to walk among the dead in the underworld and never see Pollux again. So Pollux asked Zeus, ruler of the gods, to keep them together and he put them in the sky together as the constellation Gemini. The word "Gemini" means "twins" in Latin as well.
The astrological symbol for Gemini is a stylized version of the Roman numeral two and can be found in most Gemini inspired tattoos. Other elements included would be twins, duality, symmetry or anything that could be placed in twos.