Timestamp
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A timestamp is a sequence of characters, denoting the date or time at which a certain event occurred. The term refers to rubber stamps that are used in offices to stamp the current date and time in ink on paper documents, to record when the document was received. A common example of this type of timestamp is a postmark on a letter. However, in modern times its usage has expanded to refer to digital date and time information attached to data stored in a computer or digital electronic equipment. For example, computer files contain timestamps that tell when the file was created and last modified, and digital cameras add timestamps to the pictures they take, recording the date and time the picture was taken.
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[edit] Digital timestamps
A timestamp is the time at which an event is recorded by a computer, not the time of the event itself. In many cases, the difference may be inconsequential: the time at which an event is recorded by a timestamp (e.g., entered into a log file) should be very, very close to the time of the occurrence of the event recorded.
In some cases, a timestamp can be just the numbering of events, the use of a date_time format to store a timestamp is then not mandatory.
This data is usually presented in a consistent format, allowing for easy comparison of two different records and tracking progress over time; the practice of recording timestamps in a consistent manner along with the actual data is called timestamping.
Timestamps are typically used for logging events or in a sequence of events (SOE), in which case each event in the log or SOE is marked with a timestamp. In filesystems, timestamp may mean the stored date/time of creation or modification of a file.
[edit] Examples
Examples of timestamps:
- 2005-10-30 T 10:45 UTC
- 2007-11-09 T 11:20 UTC
- Sat Jul 23 02:16:57 2005
- 1256953732
- (1969-07-21 T 02:56 UTC)-1st FootStep on the Moon, "That's one small step for [a] man, one giant leap for mankind"
[edit] Standardization
ISO 8601 standardizes the representation of dates and times.[1] These standard representations are often used to construct timestamp values.
[edit] Other meanings
Timestamp can also refer to:
- A time code (in networking or video technology)
- Unix time, the number of seconds since 00:00:00 UTC on January 1, 1970
- ICMP Timestamp
- A digitally signed timestamp whose signer vouches for the existence of the signed document or content at the time given as part of the digital signature
- The modification or access time of a file or directory in a computer file system or database
- A proof of authenticity of a person (if a picture is timestamped it proves the image isn't a download) on sites such as 4chan
[edit] See also
[edit] Notes
- ^ "ISO 8601:2004(E)". ISO. 2004-12-01. http://dotat.at/tmp/ISO_8601-2004_E.pdf. Retrieved 2010-03-07. "3.5 Expansion … By mutual agreement of the partners in information interchange, it is permitted to expand the component identifying the calendar year, which is otherwise limited to four digits. This enables reference to dates and times in calendar years outside the range supported by complete representations, i.e. before the start of the year [0000] or after the end of the year [9999]."
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