Do all PDF files have metadata? No. If you don't specify that you want metadata in your PDF files while creating them, will there be metadata? Probably.
I am frequently asked in the Acrobat classes if I know what program was used to create the source document of an exercise file. A quick tap of Ctrl-D (Cmd-D on the Mac) on the keyboard displays the Document Properties dialog box.
By clicking the Description tab, I can often state, with authority, that this document was created in Illustrator or InDesign (the Metadata tells me so). The document title, author, subject and keywords are all listed here, as well as the document's creation date, time, and the application that was used to create the source file.
From the Description tab of the Document Properties dialog box, metadata can be read, added or deleted. Additionally, there is an Additional Metadata button which allows for deeper exploration of the underlying Extensible Metadata Platform (XMP) information. This XMP information can be handed back and forth from one Adobe application to another, allowing accurate metadata to be carried through the document's workflow stages, as it is passed from one application to another. In this way, the document information present in an InDesign file is passed along to the PDF that is created from it. Exploring the options in various PDF conversion tools will often have a toggle to enable or disable certain PDF metadata conversion.
Want to remove a PDF file's metadata? Easy. Open the PDF file in Acrobat. Choose Document > Examine Document. The Examine Document Panel opens. A thorough scan of the document is initiated and metadata is one of the features that is inspected. If your document has metadata, it will be listed. At the bottom of this panel is a Remove button. With Metadata checked, click the Remove button and the metadata will be removed. Check it out by visiting the Document Properties dialog box again (the Description tab). Need to perform this on a group of files? This process can be batched by using Acrobat's Batch Processing located by choosing Advanced > Document Processing.
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