Metadata is structured information that describes, explains, locates, or otherwise makes it easier to retrieve, use, or manage an information resource. Metadata is often called data about data or information about information. Metadata is the data that you use to describe and document the research data that you have collected.
Structural Metadata is used primarily for storage of objects in a repository and for presentation. It is about the design and specification of data structures and is more properly called "data about the containers of data". Structural metadata facilitates navigation and presentation of electronic resources.
Descriptive Metadata is used for discovery of objects. It is about individual instances of application data, the data content. It is "data about data content" or "content about content" thus metacontent.
Administrative Metadata is used for managing and preserving objects in the repository.Administrative Metadata facilitates both short-term and long-term management and processing of digital collections by including
A metadata standard or schema is a set group of elements that have been standardized for a particular field. Some scientific disciplines already have established metadata standards for data sets. Additionally, some data repositories also have their own standards. One of the standards listed below might be exactly what you need to document your data. If there is not a standard already in place for your data, there are several general purpose schemas that you can adapt to your needs. Your subject specialist will be familiar with the metadata standards used in your discipline.
Metadata Concept Map by Amanda Tarbet is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
And visit Andrei Lopatenko's Resource Guide to Metadata for Science, Research, Education, and Technology for additional very specific metadata schemas.
Beyond MARC: Metadata Standards for Digital Resources / Bruce Fulton
Introductory lecture for incoming students in library and archival study programs on XML metadata standards. Included are Dublin Core, METS, MODS, EAD, PREMIS ONIX and RSS with demonstrations of OAI-PMH metadata harvesting. Concludes with the introduction of RDF, Ontologies and the Semantic Web. Published on Nov 21, 2012