A timestamp is a sequence of characters or encoded information identifying when a certain event occurred, usually giving the date and time of day, sometimes accurate to a small fraction of a second. Timestamps do not have to be based on some absolute notion of time, however. They can have any epoch, can be relative to any arbitrary time, such as the power-on time of a system or some arbitrary time in the past.

A distinction is sometimes made between the terms datestamp (DS), timestamp (TS) and date-timestamp