Unity (Node 1) is a connecting passageway to living and work areas of the International Space Station. It is the first major U.S.-built component of the station, joining Zarya (FGB). Unity will be delivered by the space shuttle with Pressurized Mating Adapter 1 prefitted to its aft port. The STS-88 shuttle crew conducted three spacewalks to attach PMA 1 to Zarya.

In addition to its connection to Zarya, the node serves as a passageway to the U.S. laboratory module, U.S. habitation module and an airlock. It has six hatches that serve as docking ports for the other modules.