In this system, the numbers consist of a first digit, from a series of ten 'Heaven Stems' (Tiangan), and the second from a series of twelve "Earth Branches" (Dìzhi).

The numbering system of 60 is used to count days, years and hours, thus arranging time into sixty-unit 'cycles', repeating it into the infinite past and future. Each year is numberedin an ever repeating 60-element cycle. So is each month, day, and hour.

Similarly, Heaven Stems and Earth Branches provided a progression of spaces in the circle of the horizon (each pair corresponding to 6 degrees in the western division of a circle into 360 degrees). Thus space and time could both be associated with units of measurement.

There are three systems used for counting and classifying the years: The Ten Heavenly Stems, the Twelve Earthly Branches(12 animals), and the Five Elements. The year of birth indicates a certain phase or aspect of a sixty-year cycle of time.

All throughout this process, is the ever present concept of Yin and Yang. The terms given to the complementary, dynamic forces that keep the universe in balance at every level.

In event predictions, hours, days, and years are associated with some pairs of Heaven Stems and Earth Branches, and depending on the combination, may be considered to be favorable or unfavorable for various activities, especially for people born at hours, days, or years associated with other combinations of Heaven Stems and Earth Branches.

Chinese astrology includes Five Elements instead of four: Fire, Earth, Metal, Water, Wood. They are agents or modifiers that subtlety alters the nature of whatever they represent.

There are ten Heaven Stems, and the pairs of Heaven Stems are aligned with the five elements and hence with various other significations connected with the 'Five Elements'.

The significations associated with the 'Five Elements' range from flavors, colors, virtues, organs, and notes of the scale. Through the linkages between Heaven Stems and the Five Elements, time and direction was even more subtly linked with these other features of human experience.

Because there are ten Heaven Branches, and because the cycle is used to count years, the Heaven Branch is predictable from the western year. A Western year ending in 0 always corresponds to a Chinese G (Geng) year. Thus a Western year ending in 1 will be a Chinese H (Xin) year, a year ending in 2 an I (Rén) year, and so on.

The ancient Chinese use the 10 Heavenly Stems and 12 Earthly Branches, but the 12 animals were designated to equate to the 12 Earthly Branches in order remember them more easily.

Therefore, the twelve Earth Branches are aligned with the famous year animals used in Chinese astrology. But they are also associated with the constellations used in the West for signs of the zodiac, and with twelve Chinese hours of the day (each two hours long by international calculation), and with directions around the horizon.

The order of the animals are as follows: Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Ram, Monkey, Rooster, Dog and Pig.

Each animal has a predominant natural element that rules over them.

In addition to each animal having a natural element, each individual year has a presiding element.

In some years, the year element is in sympathy with the animal's element, in other years it will work against. So in the non-sympathetic years, an animal might have to overcome more obstacles that the year encompasses.

There is an animal for each year, and the animal cycle takes twelve years to complete. However each animal at any specific year is associated with one of the five elements. With this in mind it takes the grand cycle 60 years to complete.