Hello. In this course, I will present to you the RDF data model. It is a standard for describing resources on the web of data. I will start by explaining what is meant by describing resources on the web, and what does the origins of this question. Then I will present to you the principles of the RDF model, we will see that it is a triple model and a graph model. Then I will introduce you to the different syntaxes that exist to serialize RDF statement. Then I will focus on the elements of model related to values, to types and the languages. Then on the element of the model enabling to represent groups of resources or groups of values. Then I will explain you the notion of name graphs and how to represent them. Finally, I will present to you the score of RDF schema which enables to describe RDF vocabularies. Let us start with, how to describe resources on the web. This question was raised for the first time perhaps in 1989 by Tim Berners-Lee in a research project proposal at Cern. As it can be seen on the figure extracting from this document, it propose a graph representation of the knowledge on the Cern documents but also on the objects described in these documents. So, concepts addressed in these documents, the resource of these documents, the organizations to which these persons belonged. You can note on this graph that its nodes and edges are labeled and typed. Quadrangle represent documents like this paper colored in yellow, cycles represent more abstract concepts like a proposal colored in orange, or notes, or news, clouds represent concepts topics like hypertext or hypermedia rectangles with rounded corners represent persons like Tim Berners-Lee in purple. The ages between the nodes of the graphs are label to links of type for example are in green, links of type includes are in red, links of type described are in blue et cetera. We will see that we find this key notion of labored type graph in the RDF model. To implement this proposal on the web, the RDF standard was born at the end of the last century. At that time, the URI standard existed to identify resources on the web and the HTTP standard to access resources. The standard was missing to describe resources for machines. It is the invention of the RDF model that allowed the creation of the web of data. As Fibia already introduced it last week, the web of data is at the intersection of three standards. URI to identify resources, HTTP to access them, RDF to describe them. If we consider the W3C standard stack, RDF stands just above the URI standout which enable to identify resources. RDF enables to represent knowledge, then comes SPARQL, to query RDF data. RDF Schema is born with RDF and later on or both to represent the vocabularies used in audio descriptions and then to reason on these descriptions. We will focus this week on RDF, the keystone of the web of data for the description of resources. To conclude this introduction, I will illustrate the key elements of the RDF model on the example description of a chocolate bar. First, the RDF about attribute enables to identify the resources to be described. This can be compared to providing the serial number of a project to uniquely identify it. In this example, we describe a particular unique chocolate bar. Second, the RDF type property enables to type a resource. This can be compared to giving a barcode to a project. In our example, the barcode enable to recognize that our chocolate bar is of a special kind produced by villars. The third key element is the RDF first label property which enables to express in natural language the nature of the resource. In our example, it enables to express in French that are produced is a bar of dark chocolate. This ensures the interaction with the consumer searching for chocolate bar to buy in his shop. Finally, RDF is an open model with an extensible vocabulary. This can be freely enriched to amount resource descriptions with information of any kind. In our example, for a chocolate bar, we would indicate at least its producer, its weight and its ingredients.