Rationale behind "Date created", "Date modified" and "Date" on Windows 10 File Explorer

Question

I am trying to understand the rationale behind Date created, Date modified and Date on Windows 10 File Explorer.

Yesterday, 30th June 2020 I downloaded a YouTube video and its subtitles in these two files shown on File explorer:

Today, 1st July, I have modified the subtitles (VTT file) adding some characters.

Date created shows the date those two files where created on my PC, 30th June 2020.

Date modified shows 1st of July 2020 for VTT file (fine, since I modified it).

Though the video file (MKV file) shows the 21st October 2018, which does not really make much sense...

Date shows the 21st October 2018 for MKV file. And 30th June 2020 for VTT file, same as Date created.

What do Date modified and Date show when files are copied/downloaded and not locally modified?

Answer 1

The "official" definitions are quite brief:

• Date Created: ( System.DateCreated )

The date and time the item was created on the file system where it is currently located. This property is automatically promoted by the file system. The Indexing Service friendly name is "create".

• Date modified: ( System.DateModified ):

The date and time of the last modification to the item. The Indexing Service friendly name is 'write'.

• Date: ( System.ItemDate ):

The primary date of interest for an item. In the case of photos, for example, this property maps to System.Photo.DateTaken.

So the underlying property Date/ItemDate maps to will vary based on the type of file and presence or absence of optional date-related EXIF metadata -- i.e. for a photo, Date taken if it exists, oterwise Date acquired if it exists, otherwise Date created.

Answer 2

What is the rationale behind Date created, Date modified and Date in Window Explorer?

I cannot find a definitive definition, but the following explains your particular case, where the MKV Date is extracted from a header in the file (It is likely that date is the video was created/recorded - look at the headers to confirm):

Date Created - the date the file was initially made

Date Modified - the date the file was last changed and saved

With regards to that Date field, the explanation seems to be:

The 'Date' column takes the earlier of 'Date created' and 'Date modified', it ignores 'Date accessed', unless there is a 'special' date field added by for instance a camera, such as an EXIF header in a JPG, which will take precedence in that Date field

Source Windows 10: Date, Date Created and Date Modified - Microsoft Community

Answer 3

I just realized that creating a new file, waiting some time and copying it, solves my doubt.

If the copied file is not modified after copying it, Date modified and Date are set to Date created value from the original file.

Answer 4

I have never been able to find any "official" definition of the "date created" and "date modified" fields which are maintained by the file system.

The rationale seems to be that "date modified" is the date when the data in the file was last updated. The "date created" is the date that a copy of the file was created on a particular disk (drive/card).

So, for example, if you create a spreadsheet on your computer drive on 1 July it will initially have a "date created" of 1 July and a "date modified" of 1 July. If you update the spreadsheet file on 6 July then the "date created" will still be 1 July but the "date modified" will be 6 July. If you then copy that file to a USB drive on 20 July, the file on the USB drive should have a "date modified" of 6 July and a "date created" of 20 July. If, instead of copying the file, it is moved, then the file on the original disk will disappear and the file on the target disk will have the same "date created" (1 July) and "date modified" (6 July). Because the filename is part of the file system directory, not part of the data in the file itself, changing the filename will not cause the "date modified" or "date created" to change.

I believe that is how it is supposed to work but whether the theory is achieved in practice depends on what you are using to do the copy or move operation. Some systems faithfully preserve the "date modified" when copying or moving by giving the copy the same "date modified" value as the original but there is nothing to stop an app being designed to write out the file copy as a completely new file - containing exactly the same contents, and having the same filename, as the original but with a "date modified" and "date created" which are both the current date/time (i.e. the date/time that the copy operation is carried out - 20 July in the above example).