A time stamp is a time value that is added to a data item to record, for example, when it was sensed, created, or updated. A time stamp may be date (28/07/1960), a precsie time (1960-07-28 03:00:00.000), or time since a well known start time (e.g. seconds since 1970). Time stamps are often meta-information aboutthe data, in contrast to dates in the main data itself (for example the birth certificate, which eocrds of the data of birth of a baby (data content), is often created and valivated several days aftre the birth itself. Howver, for status data (e.g. temperature) that is not sampled at regular intervals, the exect time at which data value was sensed is often crucial for subsequent analysis.
Used on Chap. 10: page 203