This photo shows an apple tree before it is pruned for the season. You need to cut back the tall branches so it is easier to harvest the fruit. Most of the new growth grows straight up.
You prune the branches back to a bud facing the direction you want the new branch to grow. You usually want out-facing buds so the branches grow away from the centre.
Sometimes the centre of the tree has gotten too bare and you prune the branch with a centre-facing bud so the new branch can fill the space. You do not want the centre too full though, because the fruit needs the sun to ripen.
You also prune away any weak looking branches that won't hold the weight of the fruit or branches that are crossed or rubbing.
Here is the first tree again after it has been pruned. Notice how you try to keep the tree at a manageable height so harvest can be achieved as much as possible without a ladder.
Here you can see the buds facing different directions.
Again you can see the tall branches in the back that have not been pruned yet. You can see the branches that have been left after pruning around strong enough to hold the fruit.
Some of the branches have grown twisted and crooked over the years. These get pruned out from time to time as new ones get strong enough to take their place.
Here is a row of trees all pruned and waiting for spring.