Semantic Web is a set of activities within the World Wide Web Consortium aimed at developing technologies to publish readable data. It is based on the idea of adding semantic and ontological metadata to the web. The extra information that describe the contents, meaning and relationship must be provided in a formal way, so that automatically evaluation will be possible for machines.
The objective is to improve the Internet expanding interoperability between computer systems using intelligent agents. These are computer programs that seek information without human operators.
Tim Berners-Lee tried from the beginning to include semantic information on the establishment of the internet, but for various reasons it was not possible.
The Semantic Web is an extension of the Web by which one attempts to automatically filter information accurately. It is necessary to make the information that lies on the web understandable by the machines. Especially the content, regardless of the syntax structure .
This is done taking into account the development and construction of agents responsible for processing that information and adequately filtering them. As a result, agents must retrieve and manipulate pertinent information which requires an integration without fracturing the web, but still taking full advantage of existing infrastructure.
Through this kind of semantic web, it becomes possible to get solutions to common problems in finding information through the use of infrastructure or common processes by which it is feasible to share, process and transfer information easily.
Today, the World Wide Web is based mainly on documents written in HTML, a markup language that serves mainly to create hypertext on the net. HTML can adjust the visual appearance of a document and include multimedia objects in the text (pictures , diagrams dialog, etc.).
But offers little chance for categorizing the elements that make up the text beyond the typical structural features, as with other languages (LaTeX type).
HTML allows using a visualization tool (such as a browser or user agent) to, for example, show a catalog of items for sale. The HTML code of a catalog can explain things like the document title but there is no way to specify within the HTML code M270660 if the product is a “battery Acme ” with a ” retail price ” € 200 , or if other consumer product (ie , a battery is not a musical instrument , or a pot).
The Semantic Web would look to resolve these deficiencies. This technology provides a description of the contents, such as RDF and OWL in addition to XML, the markup language designed to describe data. These technologies combine to provide explicit descriptions of web resources (whether these are catalogs, forms, maps, documentary or other object). This content is revealed as the data in a data base accessible by web or tags embedded in the document (usually in XHTML, or XML directly). These labels allow content managers to interpret.
The massive development and diffusion of the Semantic Web has some difficulties that are still hard to overcome: one is technological and the other is related to the lack of interest of webmasters.
Technologies to express the information in the format required have existed for years. Perhaps the most specialized component is OWL, which exists as W3C standard since 2004. The technology is the missing component that enables to convert automatically rich text content of web pages in OWL brands. The Semantic Web requires the creators of web pages to translate content in OWL , that can be interpreted by semantic agents.
But, this is not feasible due to the size of the Web and its unstoppable growth. Fortunately, many pages have formatted information and can perform this conversion automatically. For example, a site with thousands of movies which includes information such as title, director, release date; this information is neatly arranged and classified into a database.