Simple, complicated and complex systems — the brief introduction

Systems are very popular, in the world that we live. On the one hand they can be as small as atoms, on the other hand they can be compared to the whole universe, which is a huge system in itself. The first systems were, of course, those natural ones — the nature created them; nowadays there are also manmade systems. Despite the fact that man has observed them both for ages, not long ago was it realized that they have got, in many cases, the same structures independently on system type, are governed according to the same laws and the processes existing inside them can be simulated by interdisciplinary models. The main goal of this article is to present the basic notions connected with complex systems and the conception of the system approach.