There are two commonly used systems of romanization for Chinese words. Most westerners were introduced to the name Taijiquan through the Wade-Giles spelling, T’ai-chi ch’üan. This system is older, tends to be more cumbersome and less internally consistent in representing standard Mandarin pronunciation than the newer pinyin system. For this reason, the pinyin system, which was developed by linguists in China, and has been used as the official romanization system in the People’s Republic of China since 1953, will be used in my materials.

Louis Swaim, translator in:
Fu, Zhongwen, Mastering Yang Style Taijiquan,