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Semantic Web and Linked Data

Semantic Web and Linked Data


  • Semantic Web and Linked Data: Description by Library of Congress
  • Semantic Web and Linked Data: Description in Wikipedia
  • Semantic Web and Linked Data Quiz
  • Semantic Web and Linked Data Videos


The Library of Congress describes the Semantic Web and Linked Data as below⁽¹⁾⁽²⁾:


  • AACR2, RDA, MARC 21 record environment
  • MARC does not allow a full implementation of RDA
  • Library data is designed for the use and consumption by humans, but not integrated with the Web
  • Linked data promise a possibility to increase the visibility and usage of library data on the Web

Tim Berners-Lee describes the Semantic Web

Tim Berners-Lee, James Hendler and Ora Lassila, "The Semantic Web", Scientific American, May 2001, p. 29-37.

In 2001, Tim Berners-Lee, James Handler, and Ora Lassila published an article in Scientific American, “The Semantic Web” that describes future scenarios in which the Semantic Web …

The Semantic Web

  • "The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation."

- “A new form of Web content that is meaningful to computers will unleash a revolution of new possibilities.”

“The Semantic Web will enable machines to comprehend semantic documents and data, not human speech and writings.”

“The explicit representation of the semantics of data, accompanied with domain theories (that is, ontologies ), will enable a Web that provides a qualitatively new level of service.”

Tim Berners-Lee, James Hendler and Ora Lassila, "The Semantic Web", Scientific American, May 2001, p. 29-37.

The Semantic Web is a collaborative effort led by then World Wide Web Consortium (W3C) to provide a framework that allows data to be shared and reused across application, enterprise, and community boundaries.

W3C. What is the Semantic Web? Downloaded February 12, 2014 from

Traditional Web 

  • A collection of linked documents
    • Data exposed to the Web via HTML, pdf, etc.
    • Connections between data elements are based on human-readable hyperlinks 
    • Queried by text string matching and relevance ranking algorithms

Web 1.0

All the resources we find on the traditional document Web are information resources. There are data posted on Web sites and users simply viewed or downloaded the content. 

Darcy DiNucci, an information architecture consultant, coined the term “Web 2.0 In her 1999 article, "Fragmented Future”:

“The Web we know now, which loads into a browser window in essentially static screenfuls, is only an embryo of the Web to come. The first glimmerings of Web 2.0 are beginning to appear, and we are just starting to see how that embryo might develop. The Web will be understood not as screenfuls of text and graphics but as a transport mechanism, the ether through which interactivity happens.”

Web 2.0 and information resources

Everything that lives on the Web is an information resource:

  • Documents
  • Images
  • Audio Files
  • Video Files

Web 2.0 uses HTTP protocol to retrieve information resources

Web 2.0 has greater collaboration among Internet users, content providers and enterprises (Wikis; blogs, social networking sites, etc.)

What Is Web 2.0? []

Non-information resources and Web 3.0

All “real-world objects” that exist outside of the Web are non-information resources. Examples of non-information resources are:

  • People
  • Places
  • Abstract Concepts
  • Relationships

The Semantic Web (Web 3.0) allows the hyper linking between information resources, non-information resources and the relations between them

All  “real-world objects” that exist outside of the Web are non-information resources (also called 'other resources').

It is important to distinguish, these two types of resources, between the resources found in the current document Web and the real world resources identified in the Linked Data Web.

The Semantic Web uses the HTTP protocol to identify real world, non-information resources and the relationships between resources and non-information resources.

People, places, abstract concepts can be linked to other non-information resources and information resources and the relationships between them.

Semantic Web

  • Web of linked data
    • Information from  single pages can be found via search engines
    • Use the Web like a single global database
    • Allows machines to make logical inferences that have not been explicitly stated by human beings
    • Complex queries over multiple pages/data sources

Traditional Web vs. Semantic Web

Web of Documents (Traditional Web)
  • information resources
  • links  between documents
  • unstructured data
  • implicit semantics
  • for human consumption

Web of Data (Semantic Web)
  • “real-world objects”
  • links between things
  • structured data
  • explicit semantics
  • for machines  and human

Goal of the Sematic Web

  • “The goal of the Semantic Web is to move from a Web of Documents to an open inter-connected Web of Data.”

Bauer, Florian and Kaltenböck, Martin. (2012). Linked Open Data: The Essentials. Downloaded December 30, 2014 from:, p.25.

What enables such Web of Data?

  • Use a set of best practices for publishing and linking structured data on the Web.
  • Use technologies that are more generic, more flexible which make it easier for data consumers to discover and integrate data from large number of data sources and links

Open Linked Data  can be used to do the following:
Provide valuable, agreed-upon information in a standard, open format.

Provide mechanisms to link individual schemas and vocabularies in a way so that people can note if their ideas are “similar” and related, even if they are not exactly  the same. 

Bring all this information to an environment which can be used by most, if not all  of us. (Make data available free of proprietary software, single social networks, or web application.)

Bauer, Florian and Kaltenböck, Martin. (2012). Linked Open Data: The Essentials. Downloaded December 30, 2014 from:, p.25.

Linked Data

  • One practical application of these technologies to real-world data
  • A style of publishing and interlinking structured data on the Web so that it can be interlinked and become more useful
  • Builds upon existing well established Web technologies such as HTTP, RDF and URIs
    • Applying the Linked Data principles to legacy data sources integrates data

The term Linked Data was coined by Sir Tim Berners-Lee in his Linked Data Web architecture note [Berners-Lee, T. 2006. Design Issues: Linked Data. Last change: Date: 2007/05/02 14:30:56.]. It refers to a style of publishing and interlinking structured data on the Web.

The Wikipedia definition of Linked Data[

] is, "Linked Data is a term used to describe a method of exposing, sharing, and
connecting data on the Semantic Web. The practice emphasizes Web access to data using existing Web technologies such as URIs and HTTP.“

Linked Data builds upon existing well established HTTP technology. Valuable and good quality data exist in legacy database systems can be exploit to realize a Web of Data.

Linked Data makes the Web a HUGE database

  • Data is more useful if it links to related data, documents, and descriptions
  • Data becomes Linked Data when it links to related resources

There is a huge volume of data exists on the Web. However, many times the data is buried in in database silos in organizations. 

Linked data is about making data available in standard ways so that others can use and link to. This is essential to connect the data we have into a web. It is the unexpected reuse of information which is the value added by the web.

Basics of Linked Data

  • Use URIs as names for things 
  • Use HTTP URIs so that people can look up those names
  • When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL) 
  • Include links to other URIs, so that they can discover more things

➨   Part 2: “Semantic Data Model” 

Berners-Lee outlined these four rules of Linked Data in his design issues notes.

These rules are broad guiding principles on how to publish and interlink data in a human and machine readable way by using Semantic Web technologies.

These four principles for Linked Data will be discussed in more detail in Unit 2.

Linked Data 5-star scheme

  • Make your stuff available on the Web (*)
  • Make it available as structured data (**)
  • Use non-proprietary formats (***)
  • Use URIs to identify things, so that people can point at your stuff (****)
  • Link your data to other data to provide context (*****)
In 2010 Tim Berners-Lee introduced a 5 star rating to his Linked Data design issues page to encourage data publishers along the road to good Linked Data.

The goal is to encourage data owners to publish their data according to Linked Data principles by asking: Is our linked open data 5 star?

The first star is assigned for the big first step of making the data available on the Web (in whatever format).

All following stars are intended to make the data easier to discover, use, and understand.

The second star is assigned for making the data available in a machine readable, structured way (this can even be an Excel spreadsheet).

The third star is for using non-proprietary formats (e.g., the Open Document Format; ODS instead of XLS).

The fourth star is for using open W3C standards such as RDF to identify resources.

The fifth star is for linking your own data to other datasets.

Again, the motivation here is to have a simple stack of consecutive steps that reward improved access to data by additional stars.

Five Stars of Linked Data Vocabulary Use []

Linked Data

  • Machine-actionable data
    • Describing ➨ identifying
      • “Record” ➨ Graph
    • Mapping ➨ linking
    • String to things
“From Strings to Things” Michael Panzer

Relationship between Linked Data and the Semantic Web
  • Semantic Web is a vision of a “Web of Data”
  • Linked Data is a means to achieve that vision
  • Semantic Web is What and Linked Data is How

Current state of Linked Data in libraries

  • Developing use cases
  • Structuring, cleaning and releasing data
  • Developing new frameworks and tools
  • Exploration, prototypes and proofs of concept
  • Learning!


Several of the initiatives that have come out of the OCLC office involve offering OCLC resources as Linked Data. OCLC resources that have been released as Linked Data include the following:
VIAF (Virtual International Authority File)
* FAST (Faceted Application of Subject Terminology)  is derived from the Library of Congress Subject Headings (LCSH), FAST (Faceted Application of Subject Terminology)
* Dewey Decimal Classification System 



Change is a continuum

“As library automation technology changes and as cataloging needs change, the MARC 21 formats and related MARC 21 documentation are changing also.”

Change is 
     “NOT a one-time event.”
     “Letting go of “mastery complex,” and embracing perpetual beta.”

“Changes and change management are crucial to success of the modern library”

“Learn from the Past, Prepare for the Future” (OCLC webinar)


“As computers and technology continue to advance, important issues arise about the quality of library data and computer-based library automation systems. You need to be aware of these issues and their importance to your library.”

The Semantic Web is …

  • the Web of Data
    • Allows machines to “connect the dots”
    • Provides a common framework to share data on the Web across application boundaries

Human can easily “connect the dots” when browsing the Web but machines can’t

Semantic Web approach
  • Make data easier for machines to find, access and process
  • Express data and meaning in standard machine readable format
  • Create relations among resources on the web and interchange those data
  • Support decentralized definition and management, across the network

MARC Record

Information pulled from our MARC records using our OPAC interface is based on this model. This silos our information.


The Library of Congress is developing BIBFRAME as a general model for expressing and connecting bibliographic data.

It provides an alternative to MARC.

RDF graph of a MARC record

What you see on this slide is a small portion of the RDF graph for the MARC record on the previous slide. The record was downloaded from OCLC as a MARC RDF/SML file. The record was converted into a BIBFRAME record using MarcEdit. It was opened in Notepad ++, copied and parsed using an RDF validator which produced the graph.

with an RDF serialization (or format), thereby providing the means to connect bibliographic information to the LOD Cloud.

One way for us to do this is by connecting our records to the global Web of Data.


  • Libraries have a huge amount of identifiers
  • No other community does authorities like we do
  • We identify, structure, organize data in different ways
  • With BIBFRAME we can  leverage existing Web standards make library  content more visible on the Web 
  • Translate MARC skills and practices into a Linked Data context


Semantic Web is described in Wikipedia as below⁽⁵⁾:

The Semantic Web is an extension of the World Wide Web through standards set by the World Wide Web Consortium (W3C). The goal of the Semantic Web is to make Internet data machine-readable. To enable the encoding of semantics with the data, technologies such as Resource Description Framework (RDF) and Web Ontology Language (OWL) are used. These technologies are used to formally represent metadata. For example, ontology can describe concepts, relationships between entities, and categories of things. These embedded semantics offer significant advantages such as reasoning over data and operating with heterogeneous data sources.

These standards promote common data formats and exchange protocols on the Web, fundamentally the RDF. According to the W3C, "The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries." The Semantic Web is therefore regarded as an integrator across different content and information applications and systems.

The term [semantic web] was coined by Tim Berners-Lee for a web of data (or data web) that can be processed by machines—that is, one in which much of the meaning is machine-readable. While its critics have questioned its feasibility, proponents argue that applications in library and information science, industry, biology and human sciences research have already proven the validity of the original concept.

Berners-Lee originally expressed his vision of the Semantic Web in 1999 as follows:

I have a dream for the Web [in which computers] become capable of analyzing all the data on the Web – the content, links, and transactions between people and computers. A "Semantic Web", which makes this possible, has yet to emerge, but when it does, the day-to-day mechanisms of trade, bureaucracy and our daily lives will be handled by machines talking to machines. The "intelligent agents" people have touted for ages will finally materialize.

The 2001 Scientific American article by Berners-Lee, Hendler, and Lassila described an expected evolution of the existing Web to a Semantic Web. In 2006, Berners-Lee and colleagues stated that: "This simple idea…remains largely unrealized". In 2013, more than four million Web domains contained Semantic Web markup.


List of questions, answers, and quizzes on Semantic Web from Library and Information Science Questions Answers Quizzes. Please visit this collection and locate questions given below under the heading "Unit V - Information and Knowledge Organization and Management" where you will also find their URLs. having answers and further explanations.
  • The semantic of something is the [(a) structure of something (b) meaning of something (c) appearance of something (d) none of the above]
  • Who first coined the term "semantic web?" [(a) Larry Page (b) Tim Berners-Lee (c) Sergey Brin (d) Jerry Yang]
  • The Semantic Web is a web that is able to describe things in a way that computers can [(a) convert (b) not understand (c) understand (d) compile]
  • What's another name some people use for "semantic web?" [(a) Web 3.0 (b) Web 2.1 (c) Web 2.0]
  • "SemanticWebVision" is a future where [(a) Web information has exact meaning (b) Computers can integrate information from the web (c) Web information can be understood and processed by computers]
  • What is Linked Data? [(a) a set of techniques for expressing, exposing, and publishing data (b) a set of best practices for publishing and connecting structured data on the Web (c) using Web technologies to connect data that is related but stored in different locations]


Video 1

Title: Linked Data for the Real World Leveraging Metadata for Cataloging

Note: Slides and related resources are available at:

Presenter: Robin Fay

Publisher: Georgia Library Association

Original Published Date: May 19, 2020

Runtime: 1 hour 50 minutes



1. Library of Congress, "Semantic Web and Linked Data Quiz," (accessed February 11, 2020).

2. Library of Congress, "The Semantic Web and Linked Data Concepts: A Basic Overview," (accessed February 11, 2020).

3. Tim Berners-Lee, James Hendler and Ora Lassila, "The Semantic Web", Scientific American, May 2001, p. 29-37.

4. W3C. What is the Semantic Web? Downloaded February 12, 2014 from

5. Wikipedia, "Semantic Web," (accessed May 19, 2020)

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