The "furi" of a bonsai is a Japanese term that refers to the style or shape of the tree. It is one of the most important aspects of bonsai art, as it reflects the natural beauty and harmony of the plant. The furi can be influenced by many factors, such as the species, age, size, environment, and pruning techniques of the bonsai. There are many different types of furi, such as formal upright, informal upright, slanting, cascade, semi-cascade, literati, forest, raft, and root-over-rock. Each type has its own characteristics and aesthetic principles that require skill and creativity to achieve.