Geometric information about the current shading point. All vector coordinates are in World Space. For volume shaders, only the position and incoming vector are available. Generate a perturbed normal from a height texture, for bump mapping. The height value will be sampled at the shading point and two nearby points on the surface to determine the local direction of the normal. Allows converting a Vector, Point or Normal between World <,=>, Camera <,=>, Object coordinate space. Generate a perturbed normal from an RGB normal map image. This is usually chained with an Image Texture node in the color input, to specify the normal map image. For tangent space normal maps, the UV coordinates for the image must match, and the image texture should be set to Non-Color mode to give correct results. Information about the object instance. This can be useful to give some variation to a single material assigned to multiple instances, either manually controlled through the object index, based on the object location, or randomized for each instance. For example a Noise texture can give random colors or a Color ramp can give a range of colors to be randomly picked from. Note that this node only works for material shading nodes, it does nothing for lamp and world shading nodes. For objects instanced from a particle system, this node give access to the data of the particle that spawned the instance. This node currently only supports parent particles, info from child particles is not available. Retrieve attribute attached to the object or mesh. Currently UV maps and vertex color layers can be retrieved this way by their names, with layers and attributes planned to be added. Also internal attributes like P (position), N (normal), Ng (geometric normal) may be accessed this way, although there are more convenient nodes for this. Dielectric fresnel, computing how much light is reflected off a layer, where the rest will be refracted through the layer. The resulting weight can be used for layering shaders with the Mix Shader node. It is dependent on the angle between the surface normal and the viewing direction. The most common use is to mix between two BSDFs using it as a blending factor in a mix shader node. For a simple glass material you would mix between a glossy refraction and glossy reflection. At grazing angles more light will be reflected than refracted as happens in reality. For a two-layered material with a diffuse base and a glossy coating, you can use the same setup, mixing between a diffuse and glossy BSDF. By using the fresnel as the blending factor you’re specifying that any light which is refracted through the glossy coating layer would hit the diffuse base and be reflected off that. Node to find out for which kind of incoming ray the shader is being executed, particularly useful for non-physically based tricks. More information about the meaning of each type is in the Light Paths documentation. Manipulate how light intensity decreases over distance. In reality light will always fall off quadratically, however it can be useful to manipulate as a non-physically based lighting trick. Note that using Linear or Constant falloff may cause more light to be introduced with every global illumination bounce, making the resulting image extremely bright if many bounces are used. Some nodes are common with Composite nodes, their documentation can be found at their relevant pages rather than repeated here. Source.