Taoism is an ancient tradition of philosophy and religious belief that is deeply rooted in Chinese customs and worldview. (BBC)
Beliefs
Tao Te Ching - the Taoist bible that teaches "the Tao itself, and the power or fulfillment that results from living in
harmony with it" (Novak 146). 
Tao - the way of ultimate reality (Smith 179)
wu wei - "...a phrase that translates literally as inaction but in Taoism means pure effectiveness" (Smith 181-182)
Lao Tzu - the personified God of the Tao (BBC); “the Grand Old Master”, "[it's] obviously a title of endearment and respect, [but there is no documented founder or founding date]. All we really have is a mosaic of legends." (Smith 179) 
The Teacher
Concepts
Ch'i - it actually means vital energy. The Taoists used it to refer to the power of the Tao that they experienced coursing through them—or not coursing because it was blocked—and their main object was to further its flow. (Smith 182)
Yin and Yang are the principle of natural and complementary forces, patterns and things that depend on one another and do not make sense on their own. (BBC) 
Yin and Yang produces the Five Elements, in turn, give birth to the “ten-thousand things,” i.e. all of manifest existence. The Five Elements are Wood, Fire, Earth, Metal, and Water. (learnreligions.com)
Internal and external alchemy
Taoist physical practices, such as breath exercises, massage, martial arts, yoga and meditation are designed to transform a person both mentally and physically and so bring them into closer harmony with the Tao. (BBC) 
Many of these practices are called internal alchemy (nei-dun) by Taoists. (BBC)
Taoists also practice external alchemy (wai-dan), which involves diet and the use of minerals and herbs to promote long life. (BBC)
The One is the essence of Tao, the essential energy of life, the possession of which enables things and beings to be truly themselves and in accord with the Tao.
Taoist texts sometimes refer to the Tao as the mother and the One as the son. (BBC)
Wu and Yu -
Wu and Yu are non-being and being, or not-having and having. Wu also implies inexhaustibility or limitlessness. Some writers suggest that Wu can be directly experienced by human beings. (BBC)
Tzu Jan - phrase meaning "'that which is naturally so', meaning the condition that something will be in if it is permitted to exist and develop naturally and without interference or conflict". (BBC)
Yin represents darkness, cold, and passivity, feminine
Yang represents light, warmth, and activity, masculine