Braille
In English, there are 23 words which are replaced with a single letter. That way, the word but is contracted (shortened) to the single letter b, can to c, do to d, and so on. Even this simple rule has exceptions and special cases, which must be thought of. As an example, only the verb to do is replaced by d, the noun do (which stands for a note in music) is a different word, and is written in full.