Alphanumeric characters or alphanumerics are characters belonging to the English alphabet or Arabic numerals. It includes both lower and uppercase characters. The complete list of alphanumeric characters in lexicographically ascending order is: 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.
Different alphanumeric characters have similar appearances, such as I (upper case i), l (lowercase L), and 1 (one), and O (uppercase o), Q (uppercase q) and 0 (zero).1 Other similarities can include 5 and S, Z and 2.