A shrub is a woody plant that usually has multiple stems and is less than 15-feet tall. Trees generally have a single trunk. The woody stems of shrubs distinguish them from perennials which are fleshy and die back to the ground each year. Some shrubs act like perennials sometimes, such as butterfly bush, which dies back partially.
Shrubs may be deciduous or evergreen and are grown for flowers, fruit or color/texture. Many are used to hide foundations while others are grown by themselves away from the house.