What term refers to extra data stored in a file that gives information about the file's properties?

The term that refers to extra data stored in a file that provides information about the file's properties is metadata. Metadata serves as a descriptor that explains various attributes of the file, such as its size, creation date, last modified date, author, and file type. It allows users and programs to better understand the content and context of a file without having to open it.

In contrast, a header typically refers to the beginning part of a file or document, containing information necessary for reading or processing that file, which may include metadata for some file types, but is not solely dedicated to it. A data dictionary is a more structured format used in databases to define the meaning, structure, and interrelationships of data within database schemas, but it does not apply broadly to all file types. A footer refers to extra information found at the end of a document or file, which may contain page numbers or other summary details, but it does not focus on the core properties like metadata does.