What does this mean?
In creating FAIR digital resources, metadata can (and should) be generous and extensive, including descriptive information about the context, quality and condition, or characteristics of the data. Rich metadata allow a computer to automatically accomplish routine and tedious sorting and prioritising tasks that currently demand a lot of attention from researchers. The rationale behind this principle is that someone should be able to find data based on the information provided by their metadata, even without the data’s identifier. As such, compliance with F2 helps people to locate your data, and increase re-use and citations. Rich metadata implies that you should not presume that you know who will want to use your data, or for what purpose. So, as a rule of thumb, you should never say ‘this metadata isn’t useful’; be generous and provide it anyway!
This includes ‘intrinsic’ metadata (e.g., the data captured automatically by machines that generate data such as DICOM information for image files) as well as ‘contextual’ metadata (e.g., the protocol used, with both keywords and links to a formal protocol document), the measurement devices used (again with both keywords and links to manufacturers), the units of the captured data, the species involved (explicitly by taxon id, e.g., http://www.uniprot.org/taxonomy/9606 ), the genes/proteins/other that are the focus of the study (e.g., GO Terms), the physical parameter space of observed or simulated astronomical data sets, questions and concepts linked to longitudinal data, calculation of the properties of materials, or any other details about the experiment. See User Controlled-Metadata.