The 12 signs of the Zodiac are separated into 4 elements: Fire, Earth, Air and Water. By examining the different planets in these signs astrologers can draw an in-depth profile analysis of a subject.
Fire: Aries, Leo, Sagittarius. People with fire signs are explosive, volatile, and energetic. They are leaders, inventors and adventurers. Their weaknesses are the tendency of doing their work to their extremes and burning themselves out. The Fire attributes are best to be counterbalanced by Earth signs.
Earth: Taurus, Virgo, Capricorn. People with Earth signs are practical, cautious and reliable. If they are lacking (few Earth signs) they lack imagination and creativity.
Air: Gemini, Libra, Aquarius. Air signs are responsible for intellectual activity, thought and philosophy. People who possess many planets in the Air signs are good planners. Without Air signs, subjects may have difficulty in communication, and be weak in artistic inclination. The excess of planets in Air signs are best to be counterbalanced by planets in the Water signs.
Water: Cancer, Scorpio, Pisces. These are emotional signs. The planets in Water sign moderate the practicality of Earth, the ideas of Air, the careless energy of Fire.
In astrological interpretation, the element analysis is the most traditional. For example, many planets in the Fire sign of a chart is indicative of the subject being very lively and enthusiastic. Though this interpretation is simplistic and direct, astrologers must also consider the effect of the Qualities and Aspects of the subject's birth chart to draw a complete personality profile.