You may want to write your own input method if you do not have a standard keyboard or if you customize your code set. Many languages use a small set of symbols or letters to form words. To enter text with a keyboard, you press keys that correspond to symbols of the alphabet. When a character in your alphabet does not exist on the keyboard, you must press a combination of keys. Input methods provide algorithms that allow you to compose such characters.
Some languages use an ideographic writing system.
They use a unique symbol, rather than a group of letters, to represent a word. For instance, the character sets used in China, Japan, Korea, and Taiwan have more than 5,000 characters. Consequently, more than one byte must be used to represent a character. Moreover, a single keyboard cannot include all the required ideographic symbols. You need input methods that can compose multibyte characters.