What a terrible reputation Mars has. Because it glows red in the sky (a result of the iron oxide in its rocky soil), the Babylonians associated it with death and destruction and Pacific Islanders thought of it as the home of a giant red pig. Yet people have always fantasised about living on the red planet.
To the ancient Romans, Mars was the god of war, and many festivals were held in his honour. Ares, the Greek equivalent, was not admired. Throughout Greek mythology, Ares is constantly put down by the other gods — except for Aphrodite (Venus), the goddess of love, who adores him.
Early astrologers saw Mars as the planet of violence and bad temper. As late as the 15th century, astrologers associated it with theft, murder, battle, lechery, dishonesty, and seething malice of all sorts. Astrologers continue to associate Mars with anger, accidents, and injury. They also see Mars as the planet of action and desire. It brings will, stamina, drive, strength, energy, and the courage to go after what you want. Mars makes things happen. Mars symbolises centrifugal force (moving outward) which manifests as aggression, impulsiveness, pioneer-spirit, and an urge to discover.
The fourth planet from the Sun, Mars takes almost two years — 687 days, to be exact — to spin through the zodiac. It spends about two months in a sign. (Once every year and a half, its pattern changes, and it lingers in one section of the sky, giving that particular sign an extra jolt of Martian energy).
MARS IN A HOROSCOPE
Here we are dealing with the "male" part of ourselves, and hence the "male virtues" of ours. Mars symbolises the person’s physical energy and his need for action.
Mars is Self-projection. It symbolises the impulsive will to act; the energy focused in one direction. It gives the vital energy-source (Sun) personal motivation, direction and the will to DO.
We see one's ability to struggle, his survival instinct, and how he can accomplish superiority over others.
Mars is the planet of aggression, desire and sexuality. He is the foremost indicator for the quality and intensity of a person’s sexuality. As the “partner” of Venus, Mars acts in order to get what Venus desires – or else fights against that which Venus rejects. It is the desire to conquer; in the area of sexuality, Venus attracts the desired partner; Mars, on the other hand, wishes to conquer a partner.
It represents your physical energy, combativeness, enterprise, and courage.
It also represents the momentum, initiative and individualism.
Mars marks the necessity of breaking out of one’s “centre”, in order to enter into as-of-yet unknown territory. This “breaking out” of an already-existing balanced state causes a polarity, since the surging out of one’s “core” makes us conscious for the first time of the difference between “me” and “you”. It is therefore the task of Mars to bring dissonance into harmony, so that the first step towards the discovery and eventual assimilation of the “not-me” may be undertaken.
The position of Mars in a chart indicates an area where the native is energetic and forceful.
Symbol: 
Mars’s symbol represents the Male, just as the symbol of Venus corresponds to the Female. Mars rules the sign of Aries, and traditionally the sign of Scorpio.
The position of Mars by sign describes the way in which you take the initiative, assert yourself, and dive into a new endeavour or involvement. It represents your drive and your desires. You can read about Mars in the Signs here.
The position of Mars by house tells you where you’re most likely to act on impulse, take risks, and pursue your personal desires. You can read about Mars in the Houses here.