Most species are black or dark brown, sometimes metallic greenish-tinted, with apical whitish abdominal bands on the terga (the related genus Lasioglossum, which is otherwise often similar in appearance, has the abdominal hair bands located basally, not apically).

Many species in the genus are eusocial, with colony sizes ranging from very small (two to four bees) to large (>200).

In a few species, the cells are arranged in clusters resembling a honeycomb, but constructed of soil rather than beeswax.

A few species in the genus have extensive geographic distribution, such as Halictus rubicundus, which spans virtually the entire Holarctic region.

One of them is restricted to Southeastern USA and the Caribbean, one is Central American, and true H. ligatus is found in northern and western North America.