Blueberry is a perennial flowering plant, and the part of blueberry in vaccinia (this genus also includes cranberry, bilberry and pinecone) is indigo berry. The species in the family cyanobacteriaceae are the most common fruits sold in the form of "blueberries" and originated in North America (commercially grown high bush blueberries were not introduced into Europe until the 1930s).

Blueberries are usually upright, stratoid shrubs that can vary in size from 10 cm (3.9 in) to 4 m (13 ft). In the commercial production of blueberries, the smaller species are called "low bush blueberries" (synonymous with "wild"), while the larger species are called "high bush blueberries".

Leaves can be deciduous or evergreen, ovate to lanceolate, 1-8 cm (0.39-3.15 in) long and 0.5-3.5 cm (0.20-1.38 in) wide. The flowers are bell shaped, white, light pink or red, sometimes light green. The fruit is a berry 5-16 mm (0.20-0.63 in) in diameter with a trumpet shaped crown at the end. First it's light green, then it's red purple, and finally it's dark purple when it's mature. They are covered with a protective coating of powdery epidermal wax, commonly known as "blooming". They are sweet at maturity and have variable acidity. Blueberry bushes usually bear fruit in the middle of their growth period: the time of seed setting is affected by local conditions (such as altitude and latitude), so the peak crop in May to August (northern hemisphere) may vary depending on these conditions.