Full computer support was achieved in 2004 with the release of Unicode 4.1.0, and POJ is now implemented in many fonts, input methods, and is used in extensive online dictionaries.

The name Pe̍h-ōe-jī (Chinese: 白話字; pinyin: Báihuà zì) means "vernacular writing", written characters representing everyday spoken language.

"[5] The origins of the system and its extensive use in the Christian community have led to it being known by some modern writers as "Church Romanization" (教會羅馬字; Kàu-hōe Lô-má-jī; Jiàohuì Luōmǎzì) and is often abbreviated in POJ itself to Kàu-lô.

[11] In the early 19th century, China was closed to Christian missionaries, who instead proselytized to overseas Chinese communities in South East Asia.

[12] The earliest origins of the system are found in a small vocabulary first printed in 1820 by Walter Henry Medhurst,[13][14] who went on to publish the Dictionary of the Hok-këèn Dialect of the Chinese Language, According to the Reading and Colloquial Idioms in 1832.

[15] Several important developments occurred in Medhurst's work, especially the application of consistent tone markings (influenced by contemporary linguistic studies of Sanskrit, which was becoming of more mainstream interest to Western scholars).

[16] Medhurst was convinced that accurate representation and reproduction of the tonal structure of Southern Min was vital to comprehension: Respecting these tones of the Chinese language, some difference of opinion has been obtained, and while some have considered them of first importance, others have paid them little or no intention.

The author inclines decidedly to the former opinion; having found, from uniform experience, that without strict attention to tones, it is impossible for a person to make himself understood in Hok-këèn.The system expounded by Medhurst influenced later dictionary compilers with regard to tonal notation and initials, but both his complicated vowel system and his emphasis on the literary register of Southern Min were dropped by later writers.

Through personal communication and letters and articles printed in The Chinese Repository a consensus was arrived at for the new version of POJ, although Williams' suggestions were largely not followed.

[20] The first major work to represent this new orthography was Elihu Doty's Anglo-Chinese Manual with Romanized Colloquial in the Amoy Dialect,[20] published in 1853.

The manual can therefore be regarded as the first presentation of a pre-modern POJ, a significant step onwards from Medhurst's orthography and different from today's system in only a few details.

[21] From this point on various authors adjusted some of the consonants and vowels, but the system of tone marks from Doty's Manual survives intact in modern POJ.

[22] John Van Nest Talmage has traditionally been regarded as the founder of POJ among the community which uses the orthography, although it now seems that he was an early promoter of the system, rather than its inventor.

[10] Xiamen (then known as Amoy) was one of these treaty ports, and British, Canadian and American missionaries moved in to start preaching to the local inhabitants.

[10] Naturally, they based the pronunciation of their romanization on the speech of Xiamen, which became the de facto standard when they eventually moved into other areas of the Hokkien Sprachraum, most notably Taiwan.

[23] The fact that religious tracts, dictionaries, and teaching guides already existed in the Xiamen tongue meant that the missionaries in Taiwan could begin proselytizing immediately, without the intervening time needed to write those materials.

[26] Taking the other side, Thomas Barclay believed that literacy in POJ should be a goal rather than a waypoint: Soon after my arrival in Formosa I became firmly convinced of three things, and more than fifty years experience has strengthened my conviction.

The first was that if you are to have a healthy, living Church it is necessary that all the members, men and women, read the Scriptures for themselves; second, that this end can never be attained by the use of the Chinese character; third, that it can be attained by the use of the alphabetic script, this Romanised Vernacular.A great boon to the promotion of POJ in Taiwan came in 1880 when James Laidlaw Maxwell, a medical missionary based in Tainan, started promoting POJ for writing the Bible, hymns, newspapers, and magazines.

[46] Government activities against POJ intensified in the late 1960s and early 1970s, when several publications were banned or seized in an effort to prevent the spread of the romanization.

With the ending of martial law in 1987, the restrictions on "local languages" were quietly lifted,[55] resulting in growing interest in Taiwanese writing during the 1990s.

A valid syllable in Hokkien takes the form (initial) + (medial vowel) + nucleus + (stop) + tone, where items in parentheses indicate optional components.

Due to POJ's origins in the Christian church, much of the material in the script is religious in nature, including several Bible translations, books of hymns, and guides to morality.

[90] Besides a Southern Min version of Wikipedia in the orthography,[91] there are teaching materials, religious texts, and books about linguistics, medicine and geography.

One employed was encoding the necessary characters in the "Private Use" section of Unicode, but this required both the writer and the reader to have the correct custom font installed.

[104] In fact, the term Hàn-lô does not describe one specific system, but covers any kind of writing in Southern Min which features both Chinese characters and romanization.

[107] Examples of modern texts in Hàn-lô include religious, pedagogical, scholarly, and literary works, such as: POJ has been adapted for several other varieties of Chinese, with varying degrees of success.

[115] POJ remains the Taiwanese orthography "with the richest inventory of written work, including dictionaries, textbooks, literature [...] and other publications in many areas".

[116] A 1999 estimate put the number of literate POJ users at around 100,000,[117] and secular organizations have been formed to promote the use of romanization among Taiwanese speakers.

[121] Tâi-Lô retains most of the orthographic standards of POJ, including the tone marks, while changing the troublesome ⟨o͘⟩ character for ⟨oo⟩, swapping ⟨ts⟩ for ⟨ch⟩, and replacing ⟨o⟩ in diphthongs with ⟨u⟩.

[122] Supporters of Taiwanese writing are in general deeply suspicious of government involvement, given the history of official suppression of native languages,[9] making it unclear whether Tâi-lô or POJ will become the dominant system in the future.