The document discusses the evolution of the web from Web 1.0 to Web 2.0 and the problems with representing meaning. It introduces semantic web as representing things rather than just documents using semantic annotations in formats like RDFa, microformats and microdata. Linked data allows complex queries across a web of data by embedding semantic annotations and using common schemas like Schema.org. Major companies are now building knowledge graphs to represent structured data from sources on a linked open web.

1. Semantic Linked Data
Kouroupetroglou Praxitelis Nikolaos
Postgraduate Student
Department of Computer Science
Aristotle University, Thessaloniki, Greece
Master Studies – Web Data Mining
Instructor: Vakali Athena

2. What is about? – Origins?
 Web 1.0
◦ The Internet is a huge network of
computers that uses TCP/IP to
communicate, Lot of documents
interlinked via the internet
◦ Users have a passive role, they just
receive a page
 Web 2.0
◦ People started to interact with pages,
forums, social networks, blogs etc.
 Problem
◦ Web Pages are written in HTML,
describing the structure and not the

3. Tackle the Problem
 Semantic Web is about Things instead of
today’s Web is about Documents
 Solutions
◦ Top Down
 ◊ Need: Information Analysis, Web scraping,
natural language processing
 - Expensive! Human Intervention, hard to
maintain, legal issues
◦ Bottom Up
 ◊ Embedding sematic annotations into the web
pages

4. Semantic Technologies

5. Semantic Annotations
 RDFa, W3C
◦ Foaf, Doap, Dublin Core, Review Vocabulary,
Music Ontology, GoodRelations etc
 Microformats
◦ hReview, hCalendar, hCard, etc
 Microdata
◦ Is a HTML specification, used to nest metadata on
web pages
 So many standards, solution: Schema.org
◦ Created by Bing, Google and Yahoo in June 2011
◦ support a common set of schemas
◦ Inspired by other formats

6. Linked Data Arrival
 Almost every major Web company has now announced
their work on a knowledge graph
 Dbpedia example
◦ open-source knowledge graph since 2006.
◦ Extract structured information from Wikipedia and make it
available on the Web.
 Linked Data
◦ Web 2.0 technologies allowed websites to be re-used from
third-parties and to repurpose data on the Web, a road to Web
3.0
 Linked Data benefits
◦ can navigate in Web of Data, complex search queries

7. Summary
 “I have a dream for the Web in
which computers become
capable of analyzing all the
data on the Web”
 Tim Berners Lee, 1999, Invertor of the Web

8. Semantic Linked Data
Kouroupetroglou Praxitelis Nikolaos
Sources:
• www.w3.org
• semanticweb.org
• linkeddatatools.com
• microformats.org
• microdata wikipedia
• semantic-web-and-linked-data presentation
• tutorial-on-semantic-web-presentation
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