Daoism is a religious and philosophical system.
Daoism is a Chinese school of thought that emphasizes living in harmony with the Dao. Hence the name, Daoism. Dao translates to "way", "path" or "principle". It is the sole source and energy in the universe. It is responsible for everything that exists. However, Dao is not God, in fact is not an entity. It is pure energy or force. According to Dao, everything is connected and unified.
Daoism, along with Confucianism, is considered to be one of the two great religious and/or philosophical systems of China. Daoism borrows certain aspects from the principle of Yin Yang. It highlights the importance of complementary forces, such as light and dark, action and non-action, etc.
According to Daoism, human life is only a small part of a larger process of nature. There is flow to nature, a way, a path: the Dao. Daoism emphasizes the importance on humans not interfering with Dao. Humans, like everything else, should get along with the true nature of the world, which is Dao. This practice of going along is called wu-wei. Due to this, wu-wei is often described as ‘action through non-action’. Daoism also placed importance on "naturalness", simplicity, spontaneity, and the Three Treasures, which are compassion, moderation, and humility.
Daoism first came about in 200 BCE, which makes it over 2200 years old. It developed mainly under the Han dynasty. There are two main texts that it is influenced by; one is the Tao Te Ching, also commonly referred to as Laozi, after its author. The second is the writings of Zhuangzi. These two texts build the philosophical foundation of Taoism.
Dao was originally transcribed as Tao. Hence, Daoism is often transcribed as Taoism. However the pronunciation in the original Chinese is closer to Daoism, as opposed to Taoism.
Today, Daoism is one of the five religions that are officially recognized in China. Daoism is such an important religion that is has also traveled outside of China. It now has sizable communities in Hong Kong, Taiwan, Japan and in Southeast Asia. Daoism is also gaining popularity among the western civilization.