Any time you watch or listen to people talking about golf swings, partic ularly on the PGA tour, you will hear a lot about the plane of the swing and whether somebody is a one plane or two plane swinger of the club.
As you would expect, one plane is the description given to a club that rises on the backswing and falls on the downswing on exactly the same plane, and a two plane swing is a swing that raises on a plane line and moves off the plane line to a slightly higher plane, before dropping back to the first plane before impact with the golf ball.
The characteristics of a one plane swing are you often see a golfer with a more inclined spine angle at set up and lower hand position. This results in a steeper shoulder incline during the backswing turn and a left forearm that is flatter at the top of the swing, and is laid across the shoulder plane at the top of the backswing. The chest, shoulders and arms also turn very much in a connected fashion, and less weight is transferred to the rear leg during the backswing phase.
A two plane swing is often seen as a more conventional action. The set up posture can be taller and the backswing may be slightly flatter initially, with a rising phase during the top of the backswing, when the left arm will rise above the shoulder plane into a steep action. Dropping of the right elbow in the downswing should flatten the plane back to the original plane line halfway down the downswing before impact. More lateral weight transfer is also used in a two plane golf swing.
If you're considering whether you should try a one plane or two plane movement, it may be worth seeking out a local PGA golf professional to video your swing and discuss the basic options with you before you embark on changing your current action.