Traditional Chinese writing, conceived more than two thousand years ago, is a logographic system, in which each word of the language is represented by a separate character. To the reader, each character conveys mainly semantic, rather than phonetic, information.

This fact gives Chinese writing an inherent advantage: It can be used as a common system with which to write the country’s many mutually unintelligible dialects. Thus, speakers of dialects as divergent as Mandarin and Cantonese can communicate with one another in writing, with each character encoding the same meaning — “house,” “blue,” “think,” and so on — regardless of its pronunciation in any one dialect.

But by the same token, such a system carries a great disadvantage: Because the characters disclose little phonetic information, it is not possible, without prior knowledge, to look at a Chinese word and know how to pronounce it.

For readers, there is also the immense onus of needing to master thousands upon thousands of discrete characters to attain even basic literacy: Compare the mere two dozen or so characters that users of alphabets have to learn.

“Pinyin is not to replace Chinese characters; it is a help to Chinese characters,” Mr. Zhou explained in the interview with The Guardian. “Without an alphabet you had to learn mouth to mouth, ear to ear.”

As a result, illiteracy remained rampant throughout China well into the 20th century — affecting, by some estimates, as much as 85 percent of the population. It was also inordinately hard for foreigners to learn to read the language.

Other Romanization systems had been tried before, beginning with one developed in the late 1500s by Jesuit missionaries from Europe. Until the advent of Pinyin, the most prevalent system was Wade-Giles, the work of two British diplomats in the late 19th century.