Halictid bees and sweat bees are very similar and both are part of the family Halictidae. However, sweat bees are the best-known members. They have very noticeable colours of black to brown to metallic green. Some have abdominal stripes and yellow legs. Sweat bees are a quarter to half inch (6-12 mm) long. Compared to little carpenter bees, their abdomens are wider and pointed. Sweat bees are fairly hairy and also have thick tarsi (hind leg pollen baskets) and relatively short antennae. Their heads, when viewed from the side, are wedge-shaped.

Commonly seen in the summer, these bees are native to North America. As solitary bees, they individually build their vertical burrowed nests in the ground, usually in clay or sandy soil. Depending on the species, the females might dig their nests close together, sometimes even sharing a common entrance tunnel.

The females mate and then lay their eggs in a nest filled with pollen to provide food for the larvae when they hatch. Adult bees feed on pollen and nectar. The females have pollen collecting apparatus on their hind legs, but males do not. Sweat/halictid bees will visit a wide variety of flowers in the course of a day, their hairy bodies collecting pollen as they go, making them important pollinators of many plants. However, they are not domesticated for pollination purposes and only appear in the wild.

Besides being attracted to nectar, the bees are attracted to perspiration. On hot days, the bees will sometimes hover around or land on a person to lick their sweat. Usually they will only sting if touched or disturbed.