The Chinese zodiac has twelve signs, one for each of the twelve months of the year. They are used not only for the meaning of the twelve months, but also used for the meanings of directions and time.
To make these easier to remember, twelve different animals have been assigned to them, one for each month. The tweleve animals are:
Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Sheep, Monkey, Rooster, Dog, and Pig.
The system spread from China to many countries starting around the middle of the sixth century. These days, placing an illustration of the appropriate animal on New Year's greeting cards is very popular in Japan.