Skepticism is not a school, is a movement, a current of thought with two basic characteristics: the constant search and the critic to any epistemological claim. This peculiarity has allowed that skepticism survives the twenty-five centuries of history of philosophy. Thus we have a type of skepticism for each type of knowledge. Between the strongpoints of this movement is the necessary link between the knowledge and the inner being of things, the fact that the reality is behind the words and, therefore, hidden and the unavoidable characteristic that we can't get knowledge of this reality.