Jupiter is the largest planet in our Solar System, and has long been considered the most favorable of all the planets. It has long been a symbol of increase and abundance.
In the eastern method, it can symbolize childbirth, in that it increases the size of the family. In the western method, it can represent wealth, because it can increase the amount of money or property one handles.
Jupiter takes about 11.8 years to make a complete tour of the Zodiac. It's often noted that Jupiter's approximate 12 year cycle coincides with the Chinese Zodiac of 12 year-signs, but that isn't exactly the case. The Year Signs are based on calendar dates, and not the positions of stars and planets. There are specific ways of using the planets found in intermediate and advanced forms of Chinese Astrology, but they are very different from the predictive and relationship methods of the western system. Trying to compare apples to oranges is not very useful when either system can work well under its own rules.
Its rate of travel is about one sign per month, but during the long period of its retrograde it slows down considerably, unlike the faster planets that spend more time at their average speed.
During the several months it is retrograde, and then retracing its steps again after returning to direct motion, it may offer several opportunities that benefit you. This characteristic of Jupiter is even further amplified when the retrograde occurs in your Sun Sign, your rising sign, or the place of Mars in your birth-horoscope. Jupiter's extended retrograde period could be why the ancients revered this planet so much.
Jupiter represents the social urge in people, and nudges us to begin to become interested in the world outside our families and our childhood circumstances; its first cycle is complete around age 12, when school routines change and the hormonal cycles begin to kick in. The second cycle is at age 24, when many like to settle in to a career, take a post-graduate education, or otherwise expand their role in public life.
Jupiter's Day House is Sagittarius, and its Night House is Pisces. It shares the latter with Neptune. Jupiter can be boisterous and tends to overdo things; these traits are reflected in the nature of these signs very clearly.
It is in its detriment in Gemini and Virgo, both of whom can be crafty and evasive, and think things through before taking action. Jupiter's idealism can get in the way of Mercury's tactical thinking.
Jupiter is exalted in Cancer, whose nature is wet and cold; Jupiter brings warmth there and multiplies the things Cancer likes, as well as balancing the elemental nature.
It is fallen in Capricorn, the sign of Saturn, who limits Jupiter's growth and expansion; they have no common ground.
Its temperament is said to be warm and moist, the conditions necessary for the growth and development of living things.
In fact, Jupiter also is the planet of personal growth and expansion into the social arena. Jupiter also represents our ideals and goals, both personal and social. In India, it is called "Guru" and is considered to have a great deal of influence over one's fortune, because it is the planet that oversees religion and religious ceremony to them.
Again, there is a certain amount and quality of each planet within us. People who have a dominant Jupiter, by being born at a time when Jupiter is near the eastern horizon or highest in the sky, or those of Sun Signs Pisces, Sagittarius or Cancer with a Jupiter in "good condition" tend to be lucky. Prosperity may seem to be attracted to them, but they often have a hard time holding on to it. Often this is because they can be philanthropic; they keep wealth in circulation, and often send it where it otherwise would not go.
One of the signs of a strong Jupiter is a fondness for risk and a love of adventure, especially if travel is involved. They may overdo things a bit, but the fun-loving and jovial nature of Jupiter causes the people under it's influence to be well-liked.
Jupiter people are generous, sometimes to a fault, and honest; sometimes too honest for their own good. People born under the signs of Jupiter like playing the game of life, and are not as concerned with winning as people of other signs.
But, like every other planet, Jupiter can have negative traits as well. A Jupiter person can be fanatical, covetous, deceptive, uncommitted, a spendthrift and a practical joker. But all of these characteristics work in strange ways; the difficulty Jupiter people have with commitment has led to many brilliant insights in science, law and philosophy, simply because Jupiter would not shrug its shoulders and bow down to the conventional wisdom.