Hidden Metadata in Word, Excel and PowerPoint Files

When you send a document as a Word, Excel or PowerPoint file, you send a package that is larger than the page you looked at. It can name the author and everyone who edited it, show how long it was edited, contain old comments and the names behind tracked changes, hold hidden sheets, speaker notes and a preview picture. This guide lists where those traces live and what removing them does and does not achieve.

How the files are built

Modern Office files (.docx, .xlsx, .pptx) follow the Office Open XML standard (ECMA-376, ISO/IEC 29500). Each one is a ZIP archive of XML parts connected by relationships, with a content-types list at the top. The parts that describe the document rather than hold its content sit in a docProps folder, and the rest depends on the format.

Where traces live

• Core properties (docProps/core.xml): author, last modified by, title, subject, keywords, comments, category, status, revision, and the created, modified and last-printed dates.
• Application properties (docProps/app.xml): company, manager, template, hyperlink base, total editing time and, in a spreadsheet, the names of all sheets; in a presentation, slide titles and fonts.
• Custom properties (docProps/custom.xml): fields your organisation or a document-management system added, such as client codes.
• Thumbnail: a small picture of the first page or slide, which can show content you later changed.
• Word: comments with author and date, the author of every tracked insertion, deletion, move and format change, and a list of people who contributed.
• Excel: hidden sheets, and "very hidden" ones that the normal Unhide menu does not list; cell comments and threaded comments; links to other workbooks with file paths; hidden names.
• PowerPoint: comments and their authors, and speaker notes, which are often written for the presenter only.
• Embedded content: pictures with their own EXIF data, embedded objects, and custom XML parts added by content-management systems.

What removing metadata achieves

It removes the information stored about the document, so that a recipient cannot read the author's name, the company, the editing history that is kept in properties or the thumbnail. The Office Document Inspector & Metadata Remover shows what a file contains first and then writes a cleaned copy, working in your browser and leaving the original untouched. For PDFs, the PDF Metadata Viewer & Remover does the same job.

What it does not fix

• The content itself. A name in the text, a header, a footer, a field result or a file name is not metadata. Search the document.
• Tracked changes and comments you keep. Replacing the author name does not delete the change. Accept or reject changes, and delete comments if they must not travel.
• Hidden sheets. They still hold their data. Delete them in Excel after checking that no formula depends on them.
• Pictures and objects. Images inside the file can carry location and camera data; see Image Metadata Remover and clean them before inserting.
• Macros and links. Neither is handled; macro-enabled files are better avoided.

A routine before sharing

Save a copy, accept or reject tracked changes, delete comments and notes you do not want to share, delete hidden sheets, run the metadata remover, open the cleaned copy and read it once, then send the PDF version instead of the Office file when the recipient does not need to edit it. A signature on the document becomes invalid when it is changed, so sign after cleaning, not before. See also the guide to checking a PDF before sharing it.