What is a root position?

On keyboard you can play a chord using just the root, third and fifth. For the "C" chord, this is C E G. This is root position. The other chords would be first inversion, and the second inversion. You simply move the "root" note, or C so that it's the third note instead of the first, or E G C. The second inversion is G C E. You can achieve totally different sounds by changing the root, and also, when you change chords, it can be easier, and add a different effect.