Astrology originated in ancient Babylonia and spread from there to China, India, and the West, where different but related traditions grew up. The earliest known horoscope incorporating the principles of mature astrology dates from 409 BC. In the 2nd century AD, the astronomer Claudius Ptolemy prefaced his Tetrabiblos with a defense of astrology that proved influential. After the fall of the Roman Empire, astrology declined in the Latin west but flourished in the hands of the conquerors the Eastern Empire.

In the 12th century, astrology began to prosper in Western Europe. By the end of the 17th century, however, astrology was considered a pseudoscience by almost all learned people. Not only was it opposed to the Christian doctrines of divine intervention and human free will, but also the acceptance of a greatly expanded, Sun-centered universe raised doubt about whether the heavens were created to direct changes on Earth.

Although astrology has persisted to the present day, enjoying greater popularity in some countries than in others, it has never attracted more than an occasional scientist to its ranks since the 17th century. Periods of resurgence may correspond with times of uncertainty, especially when science and technology seem unable to provide acceptable solutions to pressing problems and when many people seem to seek a more mystical and spiritual mode of understanding the world. Many contemporary works of astrology use the terminology of recent psychological theories.

The astrological column in a newspaper today is generally based on the sign of the Zodiac in which the sun was located when a person was born. A simplified form of astrology, it implied that, all people born under the same sign anywhere in the world at any time, share common characteristics and that their daily activities should be so guided. A more individual analysis is possible when casting a horoscope by noting the relationships of the Sun, Moon, planets, and signs of the Zodiac to the time and place of one's birth.

The twelve parts on the Western Zodiac are believed to control the destiny of those born on a day assigned to each part: Aries (the Ram), Taurus (the Bull), Gemini (the Twins), Cancer (the crab), Leo (the Lion), Virgo (the Virgin), Libra (the Scales), Scorpio (the Scorpion), Sagittarius (the Archer), Capricorn (the Goat), Aquarius (the water carrier), and Pisces (the fishes).

The Korean zodiac consists of a 12-year cycle in which each year is represented by a particular animal. Associated with each animal are certain characteristics. Like the Chinese zodiac on which it is based, the Korean zodiac follows the lunar calendar.

The year in which a person was born determines his or her animal zodiac sign, and sometimes, depending on one's sex, certain signs are considered more auspicious or inauspicious. Traditionally, Koreans believed that the characteristics ascribed to one's sign predetermined one's personality and destiny. Even today, the zodiac signs are considered important factors not only in foretelling one's fortune or fate in life, but also in assessing the compatibility of prospective marriage partners.