One of the challenging advents in Computer Science in recent years was the fast evolution of parallel processors, specially the GPU - graphics processing unit. GPUs today play a major role in many computational environments, most notably those regarding real-time graphics applications, such as games. The digital game industry is one of the main driving forces behind GPUs,, it persistently elevates the state-of-art in Computer Graphics, pushing outstanding realistic scenes to interactive levels. The evolution of photo realistic scenes consequently demands better graphics cards from the hardware industry. Over the last decade, the hardware has not only become a hundred times more powerful, but has also become increasingly customizable allowing programmers to alter some of previously fixed functionalities. This tutorial is an introduction to GPU programming using the OpenGL Shading Language - GLSL. It comprises an overview of graphics concepts and a walk-through the graphics card rendering pipeline. A thorough understanding of the graphics pipeline is extremely important when designing a program in CPU, known as a shatter. Throughout this tutorial, the exposition of the GLSL language and GPU programming details are followed closely by examples ranging from very simple to more practical applications. It is aimed at an audience with no or little knowledge on the subject.
