Adobe ACROBAT 3D Manual page 730

About document metadata
Document metadata includes information about a document and its contents. Some
document metadata is created automatically when a PDF file is created: the application
used to create the PDF document, the PDF version, the file size, page size, and whether
the file is optimized for fast web view. Other document metadata can be added manually
by the creator or user of the document: the author's name, the document title, and search
keywords. Unless security is added to a document to prevent changes, you can edit any
metadata that can be set by the document creator.
Metadata is commonly used by search engines. For example, you can refine a search of
multiple PDF documents by including an author name, a keyword, or a creation date in the
search criteria if you know that the appropriate metadata has been added to the files you
are searching. (See Creating document properties.)
You can also review a document's metadata to determine a file's properties. For example,
you can look at the metadata to determine if a file has been optimized for fast
downloading from the web. If it hasn't, you can optimize the file before posting it to the
web. (See Creating document properties.)