Specifying 3D coordinates is the same as specifying 2D coordinates with the addition of a third dimension. Three conventions, Cartesian, cylindrical, and spherical, are available for entering 3D coordinates, and you can use them interchangeably. As with 2D coordinates, coordinate entry can be either absolute (measured from 0,0,0) or it can be relative to the last point specified.
Working with Cartesian Coordinates in 3D
Specifying Cylindrical Coordinates
Specifying Spherical Coordinates