Who, what, why, where, how, how much....
The Library of Congress code is a categorization of this analogy that could be considered metadata, the date is metadata, the reference URL is metadata and the writer's name is metadata for this analogy. Get it? Metadata is data that describes and give context to other data. This is one example, there are many more possible.
Feel free to be the first
Please review the linked page for context.
If you can think of something better than this,
please add it to the database