Computers keep a set of 128 codes that lists the characters of the keys on the keyboard in order known as the ASCII code set. Later extra characters were added to bring the total up to 256. All the single digit numerals, upper case and lower case letters are represented plus a number of others which are important too. However, the ASCII sets are really only useful for the European languages which employ the characters used.
Due to the small number of characters in ASCII, and the thousands of Chinese and Japanese ideogram/characters, there is a problem in uniquely coding these for each single ideogram. In China, a code set known as GB was designed for the purpose, independently, BIG5 was developed in Taiwan. In Japan, the JIS code and Shift JIS were developed to cope with their everyday computer needs. With all these competing standards there was the problem of inter communication and transportability of the codes. What linked all these varying representations was that double character codes were employed for each single character of the asian language used. Since there were 256 ASCII characters, a combination of two characters gave rise to 256 x 256 characters or, 65536 different combinations, which was more than needed to code all the known characters used, and perhaps other that could be invented.
Software which manipulated two characters and decode it into more familiar and recognisable forms could be used. Without the software, you would be left with pure junk, similarly, if you used the wrong code set, you would likewise obtain rubbish. Hence it is necessary to change the font setting of the program to accomodate the use of double character codes, and choosing from Chinese GB or BIG5, Japanese JIS or Shift JIS, or even EUC in the language interpreter.
GB is used on the Mainland of China and contains the simplified character forms that are used there. Taiwan maintained the use of tradtional characters, and incorporated it into their development of BIG5. JIS is the Japanese Industry Standard, and often used by the Japanese search engines. However, it is unusual to know that most web authors use the Shift JIS coding in their documents, making it necessary to switch between the two when going from the search engine listing to the site that you have clicked on.
Russian uses KOI 8 as one of its encoding schemes, just out of curiosity, and Korean uses