Pruning and thinning fruit and nut trees develops a strong tree structure, brings trees into early production, and maintains plant health. There are two main methods - central leader and open center. Central leader forms a pyramid shape with a central trunk and spiral scaffold branches, while open center forms a vase shape with no central leader. Proper pruning removes undesirable growth, stimulates flowering and fruiting, and uses the correct tools and pruning cuts to promote tree health.