subsurf

when you have subsurf activated you know how it makes all the edges and faces rounded when it would normally be square, well i was wondering can you make surtain faces and edges sharp and square and some round?
this could be very usful for me.
did anyone get what i was trying to say?
thanks

Select the bits you want sharp, press SHIFT + E and then move the mouse out to make the edges sharp

Cool thanks it worked, but theres a weird thing that happens if you have a box and you subsurf it and make it round then you sharpen the edges one side of the box stays round, even when you select all the edges?

Well, if I add a cube, subsurf it and then make all edges sharp - then it becomes a cube again. Could you post a screenshot or something of what you mean exactly?