Editing NTFS (section)

=== Time ===
Windows NT and its descendants keep internal timestamps as [[UTC]] and make the appropriate conversions for display purposes; all NTFS timestamps are in UTC.{{Citation needed|reason=UTC seems unlikely, as it relies on leap seconds, which Windows is known not to do|date=February 2020}}

For historical reasons, the versions of Windows that do not support NTFS all keep time internally as local zone time, and therefore so does the [[File Allocation Table|FAT]] file system. This means that when files are copied or moved between NTFS and FAT partitions, the OS needs to convert timestamps on the fly. But if some files are moved when [[daylight saving time]] (DST) is in effect, and other files are moved when [[standard time]] is in effect, there can be some ambiguities in the conversions. As a result, especially shortly after one of the days on which local zone time changes, users may observe that some files have timestamps that are incorrect by one hour. Due to the differences in implementation of DST in different jurisdictions, this can result in a potential timestamp error of up to 4&nbsp;hours in any given 12&nbsp;months.<ref>{{cite web |url=https://www.codeproject.com/Articles/1144/Beating-the-Daylight-Savings-Time-Bug-and-Getting |title=Beating the Daylight Saving Time bug and getting correct file modification times |first=Jonathan |last=Gilligan |date=28 May 2001 |website=The Code Project}}</ref>

This problem is further exacerbated for any computers for which local time zone changes sometimes (e.g. due to moving the computer from one time zone to another, as often happens with laptops and other portable devices).