This course offers a brief and accessible introduction to non-classical logics. Traditionally, a logical system is called `non-classical’ if it differs from those of classical logic. There are a great many of various non-classical logics, which are applied in philosophy, foundations of mathematics, theoretical computer science, linguistics, etc. Therefore it seems impossible to give a review of most of them in one course. For this reason, instead of trying to consider as many logics as possible, we shall focus our attention on certain fundamental issues and methods related to non-classical logics. Furthermore, although there are different kinds of semantics for non-classical logics, we shall be concerned with the so-called `Kripke semantics’, also known as `possible world semantics’. The main reason for this choice is that Kripke semantics adequately reflects the intuition behind many, if not most, non-classical logics.