Remap
In case we know the range of values of the input map we can lenearly remap (re-scale) it with this node to the other output range.
For example if some texture outputs the values in [-1..1] range for any or all of R, G, B (or X, Y, Z) channels we can remap it to the output range [0..1] easily if we type -1 for Input Min and 1 for Input Max.
This node can be useful in combination with the Gradient Ramp that reacts to the input map values in [0..1] range.