alphanumerical

Alphanumeric describes content composed only of letters and digits. The term combines alpha, for alphabetic letters, and numeric, for digits. In computing, alphanumeric typically means ASCII letters A–Z and a–z and digits 0–9. Some discussions broaden this to include letters from other scripts, but such usage is less common in basic validation tasks.

Common uses include identifiers, usernames, passwords, product codes, and serial numbers. Examples: Product123, A4B2C8, user01. Strings that also contain spaces or symbols are not strictly alphanumeric.

Implementation often relies on patterns in data validation. ASCII-only checks use a pattern such as ^[A-Za-z0-9]+$. Unicode-aware environments may accept any letter or digit, for example ^[\p{L}\p{N}]+$ in engines that support Unicode properties. In databases and programming, alphanumeric data are stored as text strings and may be subject to case-sensitivity and locale rules when sorting.

Alphanumeric constraints influence design choices, affecting search, validation, and interoperability across systems. They are common in password policies, form fields, and catalog identifiers, where a compact mix of letters and numbers is desired.