Understanding different types of timestamps

The create and modify timestamps can be somewhat confusing, so here is a brief explanation of what they are and how they are used.

There are two different sets of timestamps when it comes to PDF files:

  1. Operating system timestamps
  2. PDF Metadata timestamps

Operating system timestamps

These are the timestamps that your operating system uses to track when a file was created and last modified. They are not part of the PDF file itself, but rather part of the file system where the PDF is stored.

The operating system timestamps are typically used by the file manager to display when a file was created and last modified.

These timestamps are usually set when the file is created and/or updated by the operating system, for example when you download a PDF file it will have Created/Modified timestamps set to the time of download.

Here is where you can find these timestamps in Windows:

File Explorer timestamps

You can modify these timestamps in several ways depending on your operating system:

  • Windows: You can use a tool like Time Stamp Changer or similar app to change the timestamps. You can also use command lie tools like PowerShell or cmd to change the timestamps, there are many articles on the web how to do this.
  • Linux and macOS: You can use the touch command in the terminal to change the timestamps.

PDF Metadata timestamps

There are actuially stored in the PDF file itself and are part of the PDF metadata. These timestamps are usually displayed in the Document Properties dialog in PDF viewers.

Pdf Document Properties

When you use the Pdf Metadata Editor to edit the PDF metadata, it will update only these timestamps, leaving the operating system timestamps unchanged.