Commercial Resupply Services (2006–present)

The development of the Commercial Resupply Services (CRS) vehicles began in 2006 with the purpose of creating American commercially operated uncrewed cargo vehicles to service the ISS.^[76] The development of these vehicles was under a fixed price milestone-based program, meaning that each company that received a funded award had a list of milestones with a dollar value attached to them that they didn't receive until after they had successful completed the milestone.^[77] Private companies were also required to have some "skin in the game" which refers raising an unspecified amount of private investment for their proposal.^[78]

On December 23, 2008, NASA awarded Commercial Resupply Services contracts to SpaceX and Orbital Sciences Corporation.^[79] SpaceX uses its Falcon 9 rocket and Dragon spacecraft.^[80] Orbital Sciences uses its Antares rocket and Cygnus spacecraft. The first Dragon resupply mission occurred in May 2012.^[81] The first Cygnus resupply missionoccurred in September 2013.^[82] The CRS program now provides for all America's ISS cargo needs; with the exception of a few vehicle-specific payloads that are delivered on the European ATV and the Japanese HTV.^[83]

https://en.wikipedia.org

See this vdeo is really nice