A shrub or bush is a horticultural term rather than a strictly botanical category of a woody plant, distinguished from a tree by its multiple stems and lower height, usually less than 5-6m (15-20ft) tall. A large number of plants can be either shrubs or trees, depending on the growing conditions they experience. Small, low shrubs such as lavender, periwinkle and thyme are often termed sub-shrubs.

An area of cultivated shrubs in a park or garden is known as a shrubbery. When clipped as topiary, shrubs generally have dense foliage and many small leafy branches growing close together.

Many shrubs respond well to renewal pruning, in which hard cutting back to a ‘stool’ results in long new growth known as canes. Other shrubs respond better to selective pruning to reveal their structure and character.