Alphabet

An alphabet $\Sigma$ is any non-empty finite set used for encoding. The members of $\Sigma$ are the symbols of the alphabet.

Valid alphabets:

• $\Sigma =\{0,1\}$
• $\Sigma =\{a,b\}$
• $\Sigma =\{A,G,C,T\}$
• $\Sigma =$ all characters in the Roman alphabet

We can create strings over the alphabet, which only contain symbols from $\Sigma$.