Very simply put, metadata is "data about your data". It is highly-structured and laid out in specific fields. Often with controlled vocabularies in each field. Three metadata levels are explored below
Minimal - Basic information to enable discovery and access. Fields such as: Creator, Title, Publisher, Dates, and License/Embargo terms.
General Contextual - Administrative in nature, for example: funding agency, and grant number. Can also be methodological, for example: project information, collection process, geographical location of data collection, and data range of data collection.
Discipline Specific - Specific machine settings to enable re-use and experimental conditions for a discipline or domain.