Topiary is the art of creating sculptures in the medium of clipped trees, shrubs and sub-shrubs. The word derives from the Latin word for an ornamental landscape gardener, topiarius, creator of topia or "places", a Greek word that Romans applied also to fictive indoor landscapes executed in fresco. No doubt the use of a Greek word betokens the art's origins in the Hellenistic world that was influenced by Persia, for neither Classical Greece nor Republican Rome developed any sophisticated tradition of artful pleasure grounds.

The shrubs and sub-shrubs used in topiary are evergreen, have small leaves or needles, produce dense foliage, and have compact and/or columnar (e.g. fastigiate) growth habits. Common plants used in topiary include cultivars of box (Buxus sempervirens), arborvitae (Thuja spp.), bay laurel (Laurus nobilis), holly (Ilex spp.), myrtle (Eugenia or Myrtus species), yew (Taxus species), and privet (Ligustrum species.). Shaped wire cages are sometimes employed in modern topiary to guide untutored shears, but traditional topiary depends on patience and a steady hand; small-leaved ivy can be used to cover a cage and give the look of topiary in a few months.