In 2002, Elon Musk founded SpaceX with the intent to revolutionize the spaceflight industry. The company had a slow start: At the end of 2002 it had 14 employees, which had grown to just 160 by November, 2005. Today, it employs over 4,000 and is the fastest-growing launch services provider in the world.SpaceX is one of the few spaceflight companies that doubles as an aerospace manufacturer and launch services provider. That means it designs and manufacturers most of its rocket parts in-house, including its all-American Merlin 1D rocket engines (shown here), which power its Falcon 9 rocket fleet. Because they manufacture most of their own equipment, SpaceX has rapidly risen to become one of the most formidable competitors in the spaceflight market. In 2014, the company's CEO and founder, Elon Musk, said they could lift US Air Force satellites into orbit for $90 million per launch compared to SpaceX's competitor, the United Launch Alliance, who was charging $460 million per launch. Six years after Musk founded SpaceX, the company sent its first rocket, called the Falcon 1, to orbit. It was the first time in history that a privately-owned space company had built and launched a liquid-fueled rocket to space. For SpaceX, it was the first successful launch in the company's history.By 2012, SpaceX had completed its next-generation rocket, the Falcon 9, as well as built a spacecraft, called Dragon, that could dock with the International Space Station. SpaceX became the first privately-owned spaceflight company to send a payload to the ISS in May 2012. Today, SpaceX is the only company with a spacecraft capable of sending and returning large science-based payloads to and from the ISS, which is critical for keeping the science conducted on board relevant. The other spacecraft, Russia's Soyuz, is designed to shuttle people, not science projects. SpaceX designed the first stage of its Falcon 9 rocket (shown here) to run on nine Merlin 1D engines. That means if one of the engines shuts down during launch, the rocket can still get its payload to space and complete the mission. To compare, the first stages for the Orbital Antares rockets and Atlas V rockets run on one or two giant engines. If one shuts down, the rocket will not have enough power to reach escape velocity. Before 2013, SpaceX had achieved a number of firsts for the private spaceflight sector, but it was nothing the world hadn't already seen by government-run agencies like NASA or Roscosmos. That all changed when SpaceX began testing its first reusable rocket, called Grasshopper, in 2013, at its base in McGregor, Texas. For the first time, the world witnessed something revolutionary: a rocket that could land itself after lift-off. SpaceX retired Grasshopper in 2013.In 2014, Musk sued the federal government to lift the monopoly that SpaceX's competitor, the United Launch Alliance, had on national security launches, which are extremely lucrative contracts filed with the US Air Force. Musk said that SpaceX could provide the same services as ULA for one fifth the cost, which would not only benefit the Air Force, but also American tax payers. SpaceX was later certified to compete for these contracts in 2015.This December, SpaceX successfully landed the first stage of its Falcon 9 rocket after two earlier attempts in January and April, 2015. This is the first reusable rocket in history that has landed after completing a launch mission (sending 11 Orbcomm satellite into low-earth orbit), and was not a test, like Grasshopper or Blue Origin's New Shepard.