Signs are often associated with writing (characters) and digits and are technically realized, for example, by hole combinations, pulse sequences and current images. Examples of characters are letters of the ordinary alphabet, numerals, punctuation marks, control characters and other ideograms.
In general, a character means an information element, which in turn consists of a finite number of agreed elements, the character set, and is usually represented by a byte. One speaks of alphabetic characters if the character set is composed of the letters of the alphabet.
If the character set is made up of numeric characters, alphabetic characters, and possibly special characters (such as punctuation marks), it is referred to as alphanumeric characters. When using alphanumeric characters, it should be noted that increasing diversity of representation requires more complex codes.