Zhuyin fuhao (), Zhuyin (), Bopomofo (ㄅㄆㄇㄈ) or Mandarin Phonetic Symbols is the major Chinese transliteration system for Taiwanese Mandarin. It is also used to transcribe other Chinese languages, particularly other varieties of Standard Chinese and related Mandarin dialects, as well as Taiwanese Hokkien. 

The first two are traditional terms, whereas Bopomofo is the colloquial term, also used by the ISO and Unicode. Consisting of 37 characters and four tone marks, it transcribes all possible sounds in Mandarin. Zhuyin was introduced in China by the Republican Government in the 1910s and used alongside the Wade-Giles system, which used a modified Latin alphabet. The Wade system was replaced by Hanyu Pinyin in 1958 by the Government of the People's Republic of China, and at the International Organization for Standardization (ISO) in 1982. Although Taiwan adopted Hanyu Pinyin as its official romanization system in 2009, Bopomofo is still an official transliteration system there and remains widely used as an educational tool and for electronic input methods. 

The informal name "Bopomofo" is derived from the first four syllables in the conventional ordering of available syllables in Mandarin Chinese. The four Bopomofo characters () that correspond to these syllables are usually placed first in a list of these characters. The same sequence is sometimes used by other speakers of Chinese to refer to other phonetic systems.
What are the traditional terms for the system?
Zhuyin fuhao (), Zhuyin