Alfanumerisia

Alfanumerisia is a Finnish term used to describe strings or characters that consist of both letters and numbers. In English, the corresponding concept is alphanumeric. An alphanumeric string is typically defined as a sequence that includes alphabetic characters (letters) and decimal digits (0–9). In strict interpretations, spaces, punctuation, and other symbols are excluded.

In computing and data processing, alphanumeric strings are common for identifiers, usernames, passwords, product codes, file names, and validation routines. The specific rules about what constitutes alphanumeric can vary by system: some implementations allow only ASCII letters and digits, while others accept a broader set of Unicode letters and digits. Whether case sensitivity applies depends on the system’s encoding and policy.

Unicode support broadens alphanumeric concepts beyond ASCII. Many languages use letters with diacritics or non-Latin scripts, and modern validation can permit any Unicode letter in combination with digits. Regular expressions or validation libraries are often used to enforce allowed character sets, such as patterns that match letters and digits or that explicitly exclude spaces and symbols.

Examples of alphanumeric strings include A1b2C3 and 123abc. Depending on the definition, purely numeric or purely alphabetic strings may still be treated as alphanumeric in some contexts, but others require the presence of both a letter and a digit. Alphanumeric constraints are widely used in data entry, authentication, and database identifiers.