Metadata is the data that you use to describe and document the research data that you have collected. It contains descriptive elements, of which examples are listed below. Metadata will make your data sets searchable in an archive or repository, easily located from a citation, and easily understood by people who might want to use your data.
These are some ISO suggested minimal metadata elements to use when you are documenting your data:
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.
* Note: Geospatial Interoperability Framework discontinued.
And visit Andrei Lopatenko's Resource Guide to Metadata for Science, Research, Education, and Technology for additional very specific metadata schemas.