The search for information still depends on the knowledge available on the information sought and their uses. Founded on the principle of search content, the knowledge available on the information sought will result in the specification of information needs, often in the form of research equation. This principle applies regardless of the search agent (a human being or a search engine) and whatever the source of information (formal source - Internet, databases, etc.. informal source - humans networks, for example). The principle does not directly specify end-uses of the information sought because these uses are not included in the description of documents. And yet it is the knowledge on the final use of the information that indicates the degree of relevance. We will summarize how the concept of relevance is studied so far and present the concept of economic intelligence to better understand the complexity of the concept of relevance in this context. As we believe that the problems related to the adequacy of information can not be limited to research equations, we will present approaches from ongoing research on the relevance of information in economic intelligence. These approaches are both new approaches for document representation as well as new functionalities for the information retrieavl systems.