Vector nodes manipulate information about how light interacts with the material, multiplying vector sets, and other wonderful things which can become quite advanced. Even if you don’t have experience with vector maths, 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. 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: 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. Essentially mapping node allows the user to modify a mapping of system of 3D-coordinates. Typically used for modifying texture coordinates. 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. 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. Source.