This tutorial is about custom shaders within the XNA 4 framework. A shader (in CAD tools often called material and in XNA called effect) is a programm executed on the graphics card to manipulate the visual presentation of an object or a whole scene. A shader can describe the surface of an object and how it interacts with light (e.g. matt, glossy, shiny, reflective, bumpiness, color). Shaders can also be used for motion (morphing, water, hair), for shadows or for post effects (motion blur, depth of field). This tutorial is about integrating shaders into a XNA 4 game engine not about writing shaders in HLSL code.