The basic structure of web documents provides the desired appearance and functionality. By default,
however, the content is human-readable only. You can use additional technologies to provide meaning
to web documents, making them machine-readable and part of the Semantic Web. Many terms have
been recently introduced for emerging Semantic Web technologies, but because of the lack of formal
definitions, many of the definitions are somewhat fuzzy. For example, because of the potential to
perform actions automatically, a new era of the Web has begun, which is denoted as Web 2.0. After
gaining popularity on online community portals, some features of the Semantic Web, together with
personalization, are now referred to as Web 3.0. There is a wide choice of metadata available, along with
microformats and various annotations that can significantly extend the possibilities of web documents.
They can also considerably improve the effectiveness of web searches. RDF should be used to add
structure to the Web and change conventional search engines that apply brute-force approaches.
In this chapter, you will learn machine-readable metadata annotations and semantically
meaningful attributes. You will also become familiar with the Resource Description Framework, the
fundamental standard behind Semantic Web technologies. After reading the chapter, you will be able
not only to apply a variety of metadata annotations but also to create new vocabularies, schemes, and
ontologies, including but not limited to the following:
- General metadata in the markup: Conventional meta tags
- Microformats: Metadata provided as attribute values of markup elements
- Microdata: A metadata annotation for general metadata embedding in HTML5
- RDF: A standardized framework for Semantic Web data models
- OWL: A knowledge representation language for describing and sharing web ontologies that formally represent knowledge as a set of concepts within a domain and the relationships between those concepts
- FOAF and DOAC: Machine-readable ontologies for people and their professional capabilities
- XMP, Rich Snippets, SearchMonkey RDFa: Metadata formats for images and video clips
