GB 2312
GB2312 is the registered internet name for a key official character set of the People's Republic of China, used for simplified Chinese characters. GB abbreviates Guojia Biaozhun (国家标准), which means national standard in Chinese.
GB2312 (1980) has been superseded by GBK and GB18030, which include additional characters, but GB2312 is nonetheless still in widespread use.
While GB2312 covers 99.75% of the characters used for Chinese input, historical texts and many names remain out of scope. GB2312 includes 6,763 Chinese characters (on two levels: the first is arranged by reading, the second by radical then number of strokes), along with symbols and punctuation, Japanese kana, the Greek and Cyrillic alphabets, Zhuyin, and a double-byte set of Pinyin letters with tone marks.
There is an analogous character set known as GB/T 12345, closely related to GB2312, but with traditional character forms replacing simplified forms. GB-encoded fonts often come in pairs, one with the GB 2312 (jianti) character set and the other with the GB/T 12345 (fanti) character set.
Read more about GB 2312: Characters