What do more/less rifle barrel grooves do? What is a twist rate, and what does it do?

Rifling in the barrel causes spin on the bullet. It has a similar effect to throwing a football. The more tight the spiral on the football the farther it will go. The less spin, the more tumble. As they said before this the muskets tumbled, the football would tumble resulting in less distance. With twist rate on a rifle, i believe the higher the twist rate the more accurate the bullet will be closer. If you are shooting a far target, you want rifling, but not as much. Far targets would be about a mile. I hope i was correct and that this helps