Originally Posted by schoolman
far - farther - the farthest
-further - the furthest
Farther and further are the comparative forms of "far"
farther is used only for distance.
e.g. That village is farther than the village I live in.
That`s the farthest city ....
further means "additionally", "supplimentary"
e.g. I need further details
I received further information / data on this problem.
Further can be used as a verb ,as well.
It means : to help the progress of, to advance
e.g. You can further on with this matter though I don`t think it`s necessary.