https://www.billiards.com/the-break
So many pool games have their turning point right at the start, following a good break or a bad break, that it's no exaggeration to say the break is the most important shot. When we break the balls we want three things. First, you want to have enough force to send a ball or balls into pockets. Second, you need to scatter the balls enough to have a chance at running the rack. And third, you need enough control for the cue ball to end up in the best possible position to make your next shot.

The break shot is the hardest you will ever hit a cue ball. If you hit the cue ball this hard and your stick is not level to the table, you can bounce the ball off the table. Always keep your cue as level as possible. Everything is magnified when breaking.