In the 21st century, metadata typically refers to digital forms, but traditional card catalogs contain metadata, with cards holding information about books in a library (author, title, subject, etc.).Metadata can come in different layers: This physical herbarium record of Cenchrus ciliaris consists of the specimens as well as metadata about them, while the barcode points to a digital record with metadata about the physical record.Metadata for a Sphagnum papillosum pot that is part of a common garden experiment at Universität Greifswald
Metadata (or metainformation) is "data that provides information about other data",[1] but not the content of the data itself, such as the text of a message or the image itself.[2] There are many distinct types of metadata, including:
Descriptive metadata – the descriptive information about a resource. It is used for discovery and identification. It includes elements such as title, abstract, author, and keywords.
Structural metadata – metadata about containers of data and indicates how compound objects are put together, for example, how pages are ordered to form chapters. It describes the types, versions, relationships, and other characteristics of digital materials.[3]
Administrative metadata[4] – the information to help manage a resource, like resource type, permissions, and when and how it was created.[5]
Reference metadata – the information about the contents and quality of statistical data.
Statistical metadata[6] – also called process data, may describe processes that collect, process, or produce statistical data.[7]
Legal metadata – provides information about the creator, copyright holder, and public licensing, if provided.
Metadata is not strictly bound to one of these categories, as it can describe a piece of data in many other ways.
^Gonzalez-Perez C (2018). "Metainformation". In Gonzalez-Perez C (ed.). Information modelling for archaeology and anthropology: software engineering principles for cultural heritage (1st ed.). Springer Cham. pp. 181–189. ISBN978-3-319-72652-6.