The Progress is a Russian expendable cargo spacecraft. Its purpose is to deliver supplies needed to sustain human presence in orbit. While it does not carry a crew it can be boarded by astronauts when docked with a space station, hence it being classified as manned by its manufacturer. Progress is derived from the manned Soyuz spacecraft and launches on the same vehicle, a Soyuz rocket.
Progress has supported space stations as early as Salyut 6 and as recently as the International Space Station. Each year there are between three and four Progress flights to the ISS. A Progress remains docked until shortly before being replaced with a new one or a Soyuz (which will use the same docking port). Then it is filled with waste, disconnected, and de-orbited, at which point it burns up in the atmosphere. Due to the variation in Progress vehicles flown to the ISS, NASA uses its own nomenclature where “ISS 1P” means the first Progress spacecraft to ISS.
Progress was developed because of the need for a constant source of supplies to make long duration space missions possible. It was determined that cosmonauts needed an inflow of consumables (food, ...