Doc:2.6/Manual/Materials/Nodes/Types/Vector
Material Vector Nodes
Vector nodes manipulate information about how light interacts with the material, multiplying vector sets, and other wonderful things that normal humans barely comprehend (except math geniuses, who may not be considered «normal»). Even if you aren't a math wiz, you'll find these nodes to be very useful.
Vectors, in general, are two or three element values, for example, surface normals are vectors. Vectors are also important for calculating shading.
Normal Node
The Normal node generates a normal vector and a dot product. Click and Drag on the sphere to set the direction of the normal.
This node can be used to input a new normal vector into the mix. For example, use this node as an input to a Color Mix node. Use an Image input as the other input to the Mixer. The resulting colorized output can be easily varied by moving the light source (click and dragging the sphere).
The (face) normal is the direction of the face in relation to the camera. You can use it to do the following:
 Use this node to create a fixed direction > output Normal.
 Calcuate the DotProduct with the NormalInput. The DotProduct is a scalar value (a number).
 If two normals are pointing in the same direction the DotProduct is 1.
 If they are perpendicular the DotProduct is zero (0).
 If they are antiparallel (facing directly away from each other) the DotProduct is 1. And you never thought you would use the Vector Calculus class you took in college  shame on you!
So now we can do all sorts of things that depends on the viewing angle (like electron scanning microscope effect). And the best thing about it is that you can manipulate the direction interactively.
One caveat
The normal is evaluated per face, not per pixel. So you need enough faces, or else you don't get a smooth result

Inputs
 Normal
 3Ddirection of the face in relation to the camera. The value can be provided by another node or set manually.
Outputs
 Normal
 Fixed 3Ddirection, combined by the node.
 Dot
 Scalar value (a number), combined by the node.
Controls
 Interactive node preview
 Allows click and drag on the sphere in node center to set the direction of the normal.
Mapping Node
Essentially mapping node allows the user to modify a mapping of system of 3Dcoordinates. Typically used for modifying texture coordinates.
Mapping can be rotated and clamped if desired.
Inputs
 Vector
 The input vector (3Ddirection in relation to the camera) of some the coordinates' mapping. The value can be provided by another node or set manually.
Outputs
 Vector
 The output vector, combined by the node.
Controls
The controls of the node have been ordered in X, Y, Z order. If you want to use the clamping options, try enabling Min and Max.
 Vector type selector
 Type of vector that the mapping transforms.
 Texture
 Transform a texture by inverse mapping the texture coordinates.
 Point
 Transform a point.
 Vector
 Transform a direction vector.
 Normal
 Transform a normal vector with unit length.
 Location
 Transform position vector.
 Rotation
 Transform rotation vector.
 Scale
 Transform scale vector.
 Min
 Minimum clipping value.
 Max
 Maximum clipping value.
Vector Curves
The Vector Curves node maps an input vector x, y, and z components to a diagonal curve. Use this node to remap a vector value using curve controls.
Click and drag along the curve to create a control point and to change the curve's shape. Use the X to delete the selected (white) point.
Inputs
 Fac
 Factor. The degree of node's influence in node tree. The value can be provided by another node or set manually.
 Vector
 The input vector (3Ddirection in relation to the camera). The value can be provided by another node or set manually.
Outputs
 Vector
 The output vector, combined by the node.
Controls
 Channel selector
 Allows to select appropriate curve channel.
 X
 Curve of Xdirection.
 Y
 Curve of Ydirection.
 Z
 Curve of Zdirection.
 Reset View
 Resets view of the cuve.
 Vector Handle
 Vector type of curve point's handle.
 Auto Handle
 Automatic type of curve point's handle.
 Extend Horizontal
 Extends the curve horizontal.
 Extend Extrapolated
 Extends the curve extrapolated.
 Reset Curve
 Resets the curve in default (removes all added curve's points).