Along with Buddhism and Confucianism, Taoism is one of the main religions of China. It neither recommends austerity and non-attachment like Buddhism, nor being attached to rules, regulations and a strict discipline of Confucianism. It recommends a middle path where life is meant to be lived in harmony with nature and the 'Dao' or life-force. Naturalness, simplicity and spontaneity are considered the Three Treasures of Taoism and this says a lot about what kind of life Taoism recommends.
The 'Yin-Yang' symbol that represents Taoism suggest the need for a constant balance . Balance between the bright & dark, between day & night, masculine & feminine etc. Taoists believe more in achieving balance than a single-pointed perfection in what they do. It is a gentle, relaxed and non-competitive way to live life
Taoism essentially is a philosophical system about how to keep human behavior in accordance with the alternating cycles of nature. It was formulated by the great master Lao Tzu (also called Laozi) at around 4th century BC. Since TaiChi evolved from Taoism, it retains all the essential principles of balance and moderation in movements and form. there are lots of interesting resources on Taoism on the internet and here are some pointers.
In short, Lao Tzu worked as the Keeper of the Archives in royal court. As he grow older, he broke-free of work routine and took up a long journey into rural China and documented his wisdom in a book called Tao-Te-Ching. This became the foundation of Taoism and he gathered huge following wherever he went as people amassed to listen to his teachings. His message was so direct, simple and practical that the religion of Taoism evolved around Lao Tzu and Tao-Te-Ching