The research in the domain of knowledge representation and reasoning has always concentrated on the methods that give a good description in the domain where they are able to be used to construct intelligent applications. Description Logics are a family of languages of knowledge representation which can be used to represent knowledge of a field of applications by clear, formal and structured means. In this paper, we give an overview of what are Description Logics and their actual applications in different fields and a brief idea of extensions of Description Logic AL, as we also introduce two operators, the operator less and operator more, which allow us to obtain a new extension of the Description Logic AL.