Why do the pictures on my camera look grainy?

I have a NIKON DSLR D3000 and on the camera looking at the pictures it looks grainy. Will it be grainy when I have them printed off?

Well what setting where you shooting in
to me it sounds like you have what we called Noise
there are many programs that can help you

Graininess is film, Noise is digital

Digital noise is caused by high ISO's

lower your ISO when taking a picture and the noise will get less and less