Halictidae is a family of the order Hymenoptera consisting of small to midsize bees which are usually dark-colored and often metallic. Several species are all or partly green and a few are red.

Most halictids nest in the ground. They are commonly referred to as halictid bees or sweat bees (especially the smaller, black species), which seem attracted to perspiration and, when pinched, can give a minor sting.

Most halictid species are pollen feeders and important pollinators. A few species in the genus Sphecodes are wasp-like in appearance and live as cleptoparasites of other bees.