Metadata describe data
Metadata are data about data. We provide geospatial metadata, information about geospatial data such as images of the earth, maps and the geographical features that maps represent. Geospatial metadata are structured in a consistent way so that once you get used to the format, like cards in a library catalog, it becomes easy to find out what you need to know.
Writing metadata? Get tools and help at https://geology.usgs.gov/tools/metadata/
Managing collections of metadata
People who produce geospatial data are concerned about how to document the data resulting from their studies. But people who manage a collection of metadata have a number of different concerns that often aren't discussed in metadata-training materials, and extend beyond the relatively simple matter of making a collection accessible through the Clearinghouse. If you're managing a collection of metadata, you might be interested in these reports: