What is metadata?

Metadata is "data about data" or "information about information" that is embedded in computer files, usually automatically. Metadata is used to describe, identify, categorize, and sort files.

However, metadata can also be used to deanonymize users and expose private information.

Examples of metadata include:

In image files:
- the location where a photo was taken
- the date and time a photo was taken
- the model and serial number of the camera used to take a photo
In text document files:
- the author of the document
- changes to the document

To learn more about how metadata can be used to identify and reveal personal information, see Behind the Data: Investigating metadata.

It is impossible to reliably find and remove all metadata in complex file formats. For example, Microsoft Office documents can contain embedded images, audio, and other files containing their own metadata that Tails cannot remove.

You should remove metadata on any files before you embed them into another document.

Also, you should save files in simpler formats whenever possible. For example, instead of saving a text document as a .docx file, you can save the document as a plain .txt file.

Removing metadata using Metadata Cleaner

Tails includes Metadata Cleaner so you can remove metadata from files before you publish or share them.

Metadata Cleaner works on many file formats, including:

Image files, such as .jpeg, .png, and .gif
LibreOffice files, such as .odt and .ods
Microsoft Office documents, such as .docx, .xlsx, and .pptx
Audio files, such as .mp3, .flac, and .ogg
Video files, such as .mp4 and .avi
Archive files, such as .zip and .tar

To open Metadata Cleaner choose Applications ▸ Accessories ▸ Metadata Cleaner.

Removing metadata from the Files browser

You can also remove metadata directly from the Files browser:

Open the Files browser.
Navigate to the folder containing the files that you want to remove metadata from.
Select the files that you want to remove metadata from.
Right-click (on Mac, click with two fingers) on the files and choose Remove metadata.

Both techniques rely on the mat2 toolkit to remove metadata, so they work on the same file formats and remove the same metadata.