Editing Second (section)

==Uses==
[[Analog clock]]s and [[watch]]es often have sixty tick marks on their faces, representing seconds (and minutes), and a "second hand" to mark the passage of time in seconds.  Digital clocks and watches often have a two-digit seconds counter.

[[SI prefix]]es are frequently combined with the word ''second'' to denote subdivisions of the second: milliseconds (thousandths), microseconds (millionths), nanoseconds (billionths), and sometimes smaller units of a second. Multiples of seconds are usually counted in hours and minutes. Though SI prefixes may also be used to form multiples of the second such as kiloseconds (thousands of seconds), such units are rarely used in practice. An everyday experience with small fractions of a second is a 1-gigahertz microprocessor that has a cycle time of 1 nanosecond. Camera [[shutter speed]]s are often expressed in fractions of a second, such as {{frac|1|30}} second or {{frac|1|1000}} second.

[[Sexagesimal]] divisions of the day from a calendar based on astronomical observation have existed since the third millennium BC, though they were not seconds as we know them today.<ref>{{Cite web|title=mathematics – Ancient mathematical sources|url=https://www.britannica.com/science/mathematics|access-date=2021-09-20|website=Encyclopedia Britannica|language=en}}</ref> Small divisions of time could not be measured back then, so such divisions were mathematically derived. The first timekeepers that could count seconds accurately were pendulum clocks invented in the 17th century. Starting in the 1950s, [[atomic clock]]s became better timekeepers than Earth's rotation, and they continue to set the standard today.