Alphanumeric characters comprise the combination of the twenty-six characters of the alphabet (from A to Z) and the numbers 0 to 9. Therefore, 1, 2, q, f, m, p and 10 are all examples of alphanumeric characters. Symbols like *, & and @ are also considered alphanumeric characters.
These characters can also be used in combination. Examples of alphanumeric characters made of the combination of special symbols, numbers and the characters of the alphabet are &AF54hh, jjHF47, @qw99O. The characters of the alphabet can either be in lower case or upper case. The context of use determines whether or not case sensitivity is applied.
When coding, some alphanumeric sets exclude letters that can be easily confused with numbers. For instance, airlines and auto manufacturers both skip the lowercase letter I to avoid confusion with the numeral 1. Auto manufacturers also skip O and Q to avoid confusion with the numeral 0. Other applications do not use the letter S because of its similarity to the numeral 5, or the letter Z because of its similarity to the numeral 2.