Alphanumeric, also referred to as alphameric, is a term that encompasses all of the letters and numerals in a given language set. In layouts designed for English language users, alphanumeric characters are those comprised of the combined set of the 26 alphabetic characters, A to Z, and the 10 Arabic numerals, 0 to 9.
For some computer purposes, such as file naming, alphanumeric characters are strictly limited to the 26 alphabetic characters and 10 numerals. However, for other applications -- such as programming -- other keyboard symbols are sometimes permitted. In some usages, the alphanumeric character set may include both upper- and lower-case letters, punctuation marks and symbols -- such as @, &, and *. For languages other than English, alphanumeric characters include letter variations with accents, such as é and ç.
The mishmash of letters and numerals used for texting abbreviations is sometimes referred to as alphanumerish. As is the case with the term alphanumeric, alphanumerish can be expanded to include other characters. The grawlix, for example, which represents a non-specific profanity, is generally made up of typographical symbols that do not include either letters or numerals, but it might be considered an alphanumerish word nevertheless.