Zhuyin is a Chinese phonetic system adopted since 1913. Originally the system was called "zhuyin zimu" (phonetical alphabet), later it was renamed to "guoyin zimu" (national alphabet) and since 1930 it is named "zhuyin fuhao" (phonetic symbols). Zhuyin is popularly called "Bopomofo", since the first four symbols are "Bo", "Po", "Mo" and "Fo".
Each of the 37 symbols corresponds to one distinct phoneme. There are 21 initials (consonants) and 16 finals (combinations of vowels and, in some cases, "-n", "-ng" or "-r"). Chinese characters are transcribed with one, two or three symbols plus an accent signaling the tone of the syllable (compare with Pinyin!). However, the 1:st tone is not marked.
The symbols are
b, p, m, f, d, t, n, l:
g, k, h, j, q, x:
zh, ch, sh, r, z, c, s:
a, ai, an, ang, ao:
e, ê, ei, en, eng, er (-r):
i (yi), o, ou, u (wu), y (yü):
(or
)
There is also an extra 38:th symbol for "v", that is only used when transcribing foreign texts:
Transliterations in Zhuyin are often written on the side of regular characters:
The Zhuyin system is sometimes used in linguistic literature published in Asia. The system is particularly popular in Taiwan, where it's used for dictionaries, children's books, text books for foreigners, some newspapers and magazines and to show Taiwanese pronunciation and to spell special Taiwanese words for which no regular Chinese characters exist.
Enter the romanisation for for a syllable in Mandarin Chinese according to Pinyin or Wade-Giles, and this glossary will give you the corresponding transliteration according to Zhuyin!
Further reading:
Chinese phonetics,
hanzi,
Pinyin,
tones,
Wade-Giles 
