Bonsai trees require regular pruning and shaping, even after a desired effect is achieved. Good, healthy growth is a sign that a bonsai is in good condition and happy with its care and location. It also means that some maintenance work is in order. This can be as easy as pinching back new growth on an established tree, or as extensive as shaping, wiring and cutting a young tree as part of its first styling.
Although there's no set style or design that a tree or shrub must take to become bonsai, the overriding principle is to create a small representation of the tree in nature. More natural forms are preferred, although artistic manipulation is freely used to make bonsai trees look older or weathered, or to showcase unique but natural elements like knots or roots. This creates additional interest and helps to remind the viewer that the bonsai tree is a product of nature, and that wind, hot summers, droughts and other natural occurrences have helped shape its appearance.
If we start to look at the bonsai tree as a piece of living sculpture, it's easier to understand how carefully removing branches and encouraging others to take on different shapes and angles can help enhance the look of the tree, mimic age, create balance and conform to one of the many different classic styles of bonsai. The bonsai artist uses small gauge copper or aluminum wire to carefully wrap branches and sometimes the trunk of a bonsai tree to force the pliable wood to take on new directions or shapes. The wire is monitored carefully while it's in place to make sure that it isn't cutting into the growing wood, and after a time it's removed.