All common berries are fruits. True berries such as blueberries, grapes and currants are defined as fleshy fruits produced from one flower and one ovary. Other fruits commonly called berries, such as strawberries, blackberries, raspberries and boysenberries, are not true berries.
Most berries are not single fruits and vary in construction. Fruits such as raspberries and blackberries are called aggregate fruits because they contain many little fruits on each berry. Strawberries are in a class of their own, as the vibrant, red fruits develop from the strawberry flower, and its seeds, called pips, grow on the outside of the mature fruit.