Peirce's classifications of signs started to be developed in 1865 and it extends up to 1909. I will present on the period that begins in 1865, and that has two moments of intense production - "On a New List of Categories"and "On the Algebra of Logic: a contribution to the philosophy of notation". It is an introductory approach whose intention is to make the reader be familiar with the Peircean complex classifications of signs.