Topiary is the training and shaping of shrubs or trees through regular clipping, creating dense, well-defined shapes over time. At its best, topiary is something of an art form, plants moulded by the hand of the gardener into living sculpture. Some topiary can be surprisingly complex and on an impressive scale; some is much more simple and relatively small-scale. Either way, used well in the garden, topiary makes for an arresting and useful feature. You could include clipped balls, pyramids or domes in borders of softer planting, perhaps repeated along a path to add a touch of formality and to generate a sense of rhythm.
Topiary used in a lawn or on a terrace can bring formality and drama to the garden, as well as a sense of establishment. Some simple topiary will even thrive in large containers. Different plants bring different qualities to a topiary garden; evergreen box or yew, for example, make tight and dense growth ideal for the most intricate shapes, while other plants have a more open habit, bringing a slightly more relaxed feel. Deciduous topiary such as beech or hornbeam is looser still, but the tracery of branches visible after leaf fall adds an interesting element to the scene, especially in winter, or if used in contrast with evergreen shapes.