m01229 from USA [CC BY (https://creativecommons.org/licenses/by/2.0)]

From chinesenewyear.net:

The Rat is the first of all zodiac animals. According to one myth, the Jade Emperor said the order would be decided by the order in which they arrived to his party. The Rat tricked the Ox into giving him a ride. Then, just as they arrived at the finish line, Rat jumped down and landed ahead of Ox, becoming first.

The Rat is also associated with the Earthly Branch (地支—dì zhī) Zi (子) and the midnight hours. In the terms of yin and yang (阴阳—yīn yáng), the Rat is yang and represents the beginning of a new day.

In Chinese culture, rats were seen as a sign of wealth and surplus. Because of their reproduction rate, married couples also prayed to them for children.

Optimistic and energetic, people born in the Rat year are likable by all. They are sensitive to other’s emotions but are stubborn with your opinion. Their personality is kind, but due to weak communication skills, their words may seem impolite and rude.

On the financial side, they like saving and can be stingy. However, their love for hoarding will sometimes cause them to waste money on unnecessary things.