timestamps

A timestamp is a representation of a specific moment in time, typically consisting of a date and a time of day, and often including a time zone or offset from Coordinated Universal Time (UTC). Timestamps are used to record when events occur, to order events, and to provide provenance for data, logs, and documents. The precision of a timestamp can range from seconds to milliseconds, microseconds, or finer depending on the system.

Common standards and formats include ISO 8601, which expresses date and time in a readable form such as 2024-11-30T14:22:10Z or 2024-11-30T14:22:10+02:00; and RFC 3339, a profile of ISO 8601 used by many internet protocols. The Unix time or epoch timestamp counts the number of seconds (or milliseconds) elapsed since January 1, 1970 UTC. Databases may store timestamps using types such as TIMESTAMP WITHOUT TIME ZONE or TIMESTAMP WITH TIME ZONE, and many programming languages provide utilities to parse and format timestamps.

Time zone handling is a key consideration; converting between local time and UTC can affect interpretation and comparisons. Clock synchronization using NTP helps ensure consistency across systems. In distributed systems, logical timestamps such as Lamport clocks are sometimes used to order events when physical clocks are not synchronized. Timestamps are essential in logging, data management, version control, financial records, and any domain that requires tracking the timing of actions.