Mars
Mars governs action, energy and conflict: how a person goes after what they want and what they do when they're angry.
Governs
Mars describes a person's way of attacking and defending, their activity level, and their attitude toward risk and competition. It is also associated with sports, work that takes effort, and sexual initiative.
Mars's cycle is about two years, with roughly two months in each sign. Retrograde periods happen once every two years and are traditionally considered a time when acting directly doesn't work.
In the signs and houses
By sign, Mars shows the style of action: in Aries, direct and fast; in Libra, through negotiation; in Cancer, indirect and touchy.
By house, it shows the area where a person puts in effort and most often gets into conflict: in the sixth, at work; in the seventh, with partners; in the twelfth, with themselves.
Strong and weak placements
Domicile: Aries and Scorpio; exaltation: Capricorn. Detriment: Libra and Taurus; fall: Cancer.
In the tradition, Mars is the "lesser malefic," a planet of difficulties. Modern astrology treats it more gently: as energy that needs an outlet rather than a source of trouble.