Let's now turn our attention to the topic of shaders. This is a feature that is available in OpenGL (ES) 2.0 and above as it makes use of the so-called Programmable Pipeline. Shaders are usually small programs, which allow us to take over control of certain stages in the rendering process to define the way a scene should be rendered by the graphics processor. In consequence, shaders are an important building block in today's computer graphics and are also an extremely powerful tool to create all sorts of (special) effects that would be very hard to realize otherwise. For the sake of simplicity, we will only discuss vertex and fragment shaders here.
Note
Fragment shaders are also called pixel shaders. Unfortunately, this is a bit misleading as this type of shader actually operates on fragments instead of pixels.
Consider the following list of reasons as to why shaders are generally useful and highly recommended to be in the toolkit of every (graphics) programmer...