Alphanumeric is a combination of the words "
alphabetic" and "
numeric" and is used as an
adjective to describe a particular string or
character set. The classic example of an alphanumeric string is that of a
filename on a computer.
Because the alphanumeric character set is a super set of both the "alphabetic" and "numeric" character sets, it can be said that any text that can be represented in either the alphabetic or numeric set may is also alphanumeric, even though it does not contain characters from the other subset.
Different systems may include some limited punctuation within the definition of alphanumeric or extend this to include characters outside of the standard English character set though still within the Roman alphabet such as é and ¸la;.
Other classic alphanumeric strings include text messages on cell phones, e-mail addresses, and driver licenses ids.