1. Metadata ("Data about data")

What is Metadata?

Metadata is the information we create, store and share to describe things, objects, data or services. And it helps us to obtain the knowledge we need about these things, objects, data, or services.

Every day we use metadata in order to find out about thing we are interested or use. We listen to music; post photos on Instagram; locate video on YouTube; connect with others via social media; and store contact lists on our mobile devices. All of this content comes with metadata—information about the item’s creation, name, topic, features, and so on. Metadata is key to the functionality of the systems holding the content, enabling users to find items of interest, record essential information about them, and share that information with others.

This video below introduces a metadata, and discusses descriptive and structural metadata types (for more information visit the webpage of authors.)

5 minutes about metadata

Metadata encodings

Metadata can be found in a variety of forms and encodings. In traditional information systems design, it might be stored as fields in relational database tables. A collection of metadata in this context is known as a record

XML. In the 2000s, XML (eXtensible Markup Language) emerged as a commonly used encoding, transfer, and occasional internal system storage mechanism for metadata. Metadata in XML exists as sets of files, called XML documents. XML defines elements, tags that signify that the values inside them have a certain meaning. Elements can also have other elements inside them, and it is from this feature that XML documents gain their structure. The use of XML is not limited to descriptive metadata; many different types of metadata can be stored in XML documents. To explore more about XML go to XML Tutorial or XML -Overview

XML supports multilingualism of metadata by providing a predefined attribute to indicate the language in which an element’s value appears.

RDF (Resource Description Framework) is a set of W3C specifications designed for metadata on the Semantic Web. Whereas XML models information as a tree, RDF models it as a graph, with small bits of information each connected to other small bits of information. No one entity or piece of data has primary importance in a graph; the network of information can be accessed equally at any point.  An RDF graph is best viewed as a whole, or as a simplified subset used in a given context for a given purpose. If you would like to explore RDF visit RDF Tutorial