Linked Data is theway that the Semantic Web has to link the different data that are distributed on the Web, so that is referenced in the same way they do the links on Web pages.
The Semantic Web is not just the publication of data on the Web, but they can be linked to others, so that people and machines can explore the web of data, being able to related information referred from other initial data.
In the same way that the web site of the hypertext, the web of data is built by documents on the web. However, unlike the web of hypertext, where links are relationships between points of the documents written in HTML, the data link arbitrary things described by RDF.
For example, assuming that a directory of companies publishes specialized informationon relative to organizations, such as size or professional area, you may want to indicate also information about location. There are web sites with large geographic databases with detailed information on locations, the business directory can refer to the geographical data that are arranged in the external source. Thus, the initial data of the organization are enriched with information provided by experts in the geographical area.
As we can read in the book of Tom Heath and Christian Bizer ( Linked Data: Envolving the Web Into a Global Data Space, 2011):
The term Linked Data refers to a set of best practices for publishing and interlinking structured data on the Web. These best practices were introduced by Tim Berners Lee in his Web architecture note Linked Data and have become known as the Linked Data principles. These principles are the following:
1. Use URIs as names of things
2. Use HTTP URIs, so that people can look up those names.
3. When someone looks up a URI, provide useful information, using the standards (RDF, SPARQL)
4. Include links to other URIs, so that they can discover more things
* Linked data. (2012, April 27). In Wikipedia, The Free Encyclopedia. Retrieved 21:15, May 8, 2012, from http://en.wikipedia.org/w/index.php?title=Linked_data&oldid=489499805
* Linked Data: Envolving the Web Into a Global Data Space by Tom Heath and Christian Bizer (2011) http://books.google.es/books?id=OFv59Wcfkx8C&printsec=frontcover&dq=linked+data&hl=es&sa=X&ei=-oypT5eKM8n98QPPuP3UCg&ved=0CD8Q6AEwAQ#v=onepage&q=linked%20data&f=false