There are three ways to turn a drill bit. The "old" way is to turn the "kelly" via the rotary table thus turning the entire drill string with bit on bottom. 2nd way is newer technology which has a "top drive" unit that is mounted just under the traveling blocks in the derrick and runs up and down on a track. It screws into the drill string there (on Top) and is hydraulically spun. So you can drill a 90' stand of drill pipe at a time instead of a single 30' joint. The way to drill directional and horizontal, which is what they are doing in the Marcellus and other natural gas plays, is to use a "mud motor". It is a heavy walled pipe that has a rotor on the inside. The last couple of feet has a section that is free turning. The force of the "mud" or drilling fluid passing through the rotor turns the bit. So the only part of the drill string that turns is the last couple of feet of the mud motor. Mud motors have a "bent sub" that bends the motor a few degrees off center. Once your bend is established the bit will continue in that direction and "build" angle the deeper you go. You can build up to a 90 degree angle and then straighten it out and drill horizontally. A monitoring sytem called MWD (measurement while drilling) gives you a constant read out of tool face orientation and azimuth. So if your tool face, the direction your drilling in, starts to "walk" out then you turn the drill string a little bit to re-adjust the tool face back to your orientation. Directional companies claim that if you could bury a coke can 10,000' deep any direction within a mile from the well they could drill down and hit it. This technology is what makes drilling so much less of an enviromental impact than it used to be. You can drill dozens of wells going off in different directions from the same well pad. So one well site, one road into it and dozens of wells. Also a new practice is starting to get popular. Multi-Lateral drilling. Drill a vertical hole down to the pay zone. Kick off horizontal and drill into the pay zone several thousnad feet. Then pull back and kick off in the opposite direction and drill horizontal several thousand feet in that direction. I have seen as many as 4 laterals off of one vertical bore. Most pay zones are only a few hundred feet thick and many are less than a hundred. So in conventional vertical wells you drill down through the pay zone and expose maybe 200' of oil or gas bearing formation. The oil and gas seeps from the exposed formation into the vertical bore hole and is brought to the surface. Now imagine drilling into that same 200' thick pay zone and then "kicking out" orizontal and exposing several thousand feet of formation. You can see the advatages to the horizontal technology. I don't know if I clarified or confused.