Programming languages can be classified according to two different criteria. Firstly we can classify languages according to the metaphor that they obey, for example, we can describe languages as being Procedural,Imperative, Declarative, Functional, Object Oriented and so on. Secondly we can classify languages according to their behavioral characteristics asking is they are concurrent, parallel, fault-tolerant, or real time and so on. In this talk I'll talk about the different programming metaphors and the behavioral characteristics of commonly used languages and operating systems. I'll hope to show how use of an inappropriate metaphor can make simple problems embarrassingly difficult, and how hard problems become trivial by correctly choosing the metaphor and the characteristics of the languages.