Last accessed date of file

Last accessed date indicates when a file was accessed the last time. This attribute differs from modified date. While modification date indicates the last changes in file contents, the last accessed date does not necessarily presuppose changes of content. When a file is modified, modification and last accessed date is set to the same value. However if the file is only opened for viewing, copied, moved, or in other words - if file or folder is used in any way, last accessed date is changed to current one.

Like all file attributes, last accessed date is recorded in file system, not in the file contents. This file property does not interfere with the date stamps that are stored in the file itself. Various applications put their own date and time records in the file contents or meta-tags like Microsoft Office products.

Any viewing, copying or moving of the documents, images and other files automatically alters last accessed date stamp of the file.

Notes:
  • Sometimes last accessed time is changed due to some programs operation with files or folders. It might be antivirus software which accesses file for virus scanning purpose or Windows Explorer that extracts icon from executable file.
  • Resolution of file last accessed date is 1 hour for NTFS and 1 day for FAT.
  • For improved file system performance, Last Access time update is switched off since Windows Vista by default (also, Windows 2008 / 2008 R2, Windows 7). Thus, Last Access time attribute is set upon creating file and not changed afterwards even if file is modified. However, it is possible to enable Last Access time updates if necessary.
    To enable updates, open Registry Editor by typing regedit in Search input on Start Menu, locate HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem path entry and change NtfsDisableLastAccessUpdate value data to 0. After this change, the system has to be restarted. Alternatively, run the following command with administrator rights:

C:\>fsutil behavior set disablelastaccess 0

Reference:
http://www.febooti.com/products/filetweak/online-help/file-last-accessed-date.html