The SKK input method is designed for entering Japanese text. The input method was originally invented by Masahiko Sato in 1987 and it is quite different from other Japanese input methods in the way it handles input.
While other Japanese input methods treat input as a sentence, SKK treats it as a word and leaves control of sentence construction to users. Though it is not what normal users expect, advanced users can input Japanese with SKK more efficiently.
Input methods are typing systems allowing users to input complex languages. They are necessary because these contain too many characters to simply be laid out on a traditional keyboard.