Zhùyīn 注音, also known as “bopomofo” (for the sounds of the first four characters), is a phonetic script used to transcribe Chinese. It is widely used in Taiwan 台灣 even though it has been officially superseded by Hanyu pinyin. Many people consider it to be a superior system for learning Chinese whereas others cite the pragmatism of using the Latin alphabet to represent the language in an everyday setting. I haven’t much personal experience with zhuyin but see many advantages to its use.
I captured this image in an independent bookstore not far from Gongguan MRT in Taipei 台北.