Not exactly.
One of the problems with digital is that the sensors do not have the dynamic range that we used get with film. So, when you take a nice landscape the chances are that you either burn out the sky or lose some detail in the shadows (known as clipping). Shadow detail is not so bad, you can often tease this out, but burnt highlights are a lost cause, there's nothing there to rescue. For this reason we used ND grads and what these do is allow you to expose for the shadows while the ND holds back the highlights in the sky. There are a number of ND grad combinations; ND2, 4 & 8, then Light, Medium, Soft, Full etc. which relates to the coarseness of the transition from clear to ND. Get this under your belt and you can start having fun with the coloured grads, Red, Tobacco, Green etc.
I warn you, this is a slippery slope. Once you get into these filter systems you will be forever searching for the next one and you'll need a whole new camera bag just to carry them!
