What is a non alphanumeric character?

Non alphanumeric characters are any characters that are not letters or numbers. This includes punctuation marks, symbols, and special characters such as !, @, #, $, %, ^, &, *, and so on. Non alphanumeric characters are commonly used in writing and in computer programming to convey different meanings and functions. They are also used in passwords to increase security by including a mix of different character types.