are substituted (referred to as simple substitution). It can be demonstrated by writing out the alphabet twice, once in regular order and again with the letters shifted by some number of steps or reversed to represent the ciphertext alphabet (or substitution alphabet).

The substitution alphabet could also be scrambled in a more complex fashion, in which case it is called a mixed alphabet or deranged alphabet. Traditionally, mixed alphabets may be created by first writing out a keyword, removing repeated letters in it, then