Metadata represents data about data. Metadata enriches the data with information, which makes it easier to discover, use and manage.
There is a wide variety of metadata depending on its purpose, format, quality and volume. Some of the widely used categories of metadata are: descriptive, structural, administrative and statistical.
One example of metadata is everything written on a letter envelope to help the actual content – the letter – get delivered to its recipient. As another example, HTML tags instruct web browsers how to layout the pages to make it easier for humans to read them and follow references to other pages.
Semantic metadata helps computers to interpret the meaning of the data via references to concepts, formally described in a knowledge graph. Semantic metadata is often part of knowledge graphs itself.
The most widespread definition of metadata has it that metadata is “information about data”. Thankfully, there’s another way to look at it, apart from the dry description. “A love note to the future” is how Jason Scott refers to metadata.
Metadata, you see, is really a love note – it might be to yourself, but in fact it’s a love note to the person after you, or the machine after you, where you’ve saved someone that amount of time to find something by telling them what this thing is.
Cit. Jason Scott’s Weblog
Describing physical and digital objects is what metadata is about. It helps the classification, access and storage of digital assets of all kinds. It is with metadata that the encoding of knowledge within any data element is possible.
Metadata comes in many shapes and flavors, carrying additional information about where a resource was produced, by whom, when was the last time it was accessed, what is it about and many more details around it.
Similar to the library cards, describing a book, metadata describes objects and adds more granularity to the way they are represented. Three main types of metadata exist: descriptive, structural and administrative.
Metadata is everywhere, it is the digital trail of everything we do in the information space. The moment we get digital, there’s metadata involved.
Examples of metadata span from the size and the subjects of our emails through the dates of the files we have created, who last accessed or modified them, through the sensor data from our smartphones to the latest movie we searched for on YouTube. Facilitating the navigation and presentation of resources metadata also includes tags, semantic annotations, page numbers, sections of documents and resources, and more.
Another, more recent, example is how RDF-star (also known as RDF*) offers an alternative approach to annotating statements in RDF by allowing one to attach metadata to edges in a knowledge graph.
Metadata underlies every digital object and is critical to the way they are managed, organized and used.
When created and handled properly, metadata serves the clarity and consistency of information. Metadata facilitates the discovery of relevant information and the search and retrieval of resources. Tagged with metadata, any digital object can be automatically associated with other relevant elements and thus easy to organize and discover. This helps users make connections they would not have made otherwise.
With metadata you can:
Metadata is powerful, but semantic metadata is even more powerful.
Semantic metadata (that is metadata expressed with the help of Semantic Technology) makes those “love notes to the future” reach their full potential.
Managing metadata with Semantic Technology in mind makes things happen automagically (to use a word by David Weinberger from his book Everything is Miscellaneous).
Semantic metadata makes everything easier to arrange and connect. And when everything is interlinked, elements are more easily remixed, put together, repurposed and ultimately made sense of.
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