There are many species of bees. The smallest bee is the dwarf bee and it is about 2.1 mm (5/64") long. The largest bee in the world can be as large as 39 mm (1.5"). The most common type of bee in the Northern Hemisphere are the many species of Halictidae, or sweat bees and they are small and often mistaken for wasps or flies.

The most well-known bee species is the Western honey bee, which, as its name suggests, produces honey, as do a few other types of bee. Human management of this species is known as beekeeping or apiculture.

Bees are adapted for feeding on nectar and pollen, the former primarily as an energy source, and the latter primarily for protein and other nutrients. Most pollen is used as food for larvae.

Bees have a long proboscis (a complex "tongue") that enables them to obtain the nectar from flowers. Bees have antennae almost universally made up of thirteen segments in males and twelve in females, as is typical for the superfamily. They all have two pairs of wings, the hind pair being the smaller of the two; in a very few species, one sex or caste has relatively short wings that make flight difficult or impossible, but none are wingless.