Dateformat

Dateformat is the convention used to express a calendar date as a string. It defines the order of year, month, and day and may include time information, era, and textual or numeric month names. Date formats are chosen to suit culture, language, and software requirements.

Regional and historical differences produce multiple common orders: year-month-day (Y-M-D), month-day-year (M-D-Y), and day-month-year (D-M-Y). Separators vary (hyphens, slashes, or dots). Two-digit years increase ambiguity and can cause data corruption when unclear about the century.

Standards and best practices: ISO 8601 specifies the unambiguous form YYYY-MM-DD, often with a time component and time zone (e.g., 2024-12-17T15:30:00Z). RFC 3339 and similar standards address timestamps with a time zone. For user interfaces, locale-aware formatting uses the reader's regional settings.

In software, formats are implemented via libraries and format strings that map date components to symbols, such as strftime patterns, Java SimpleDateFormat, or JavaScript Intl.DateTimeFormat. Storing dates in a numeric or standardized textual form helps avoid misinterpretation in data exchange.

Choosing a dateformat depends on audience and use case; for interchange, ISO 8601 is preferred; for display, locale-sensitive formatting is common; for internal storage, use a universal representation like a timestamp.