Chinese zodiac astrology is represented by 12 animals. These animals all are:

1. Rat
2. Ox
3. Tiger
4. Rabbit
5. Dragon
6. Snake
7. Horse
8. Goat
9. Monkey
10. Rooster
11. Dog
12. Pig

There are a wide variety of legends concerning the origins of the Chinese zodiac astrology. One of these is in imitation by Buddha to all the animals of the world. Ironically enough, only the 12 above showed up and therefore Buddha rewarded them by dedicating a year to each animal.
After much contemplation Buddha decided the order of the Chinese zodiac astrology based on its the order in which the 12 animals showed up to visit him. While the cycle repeats itself every 12 years, Chinese zodiac astrology is based on the lunar year unlike Western astrology.
Since the Chinese use the lunar year instead of the solar year this is why Chinese new year, falls between January and February.