Iridium Communications Inc. (formerly Iridium Satellite LLC) is a publicly traded American company headquartered in McLean, Virginia, United States. Iridium operates the Iridium satellite constellation, a system of 80 satellites: 66 are active satellites and the remaining fourteen function as in-orbit spares. Iridium Satellites are used for worldwide voice and data communication from handheld satellite phones, satellite messenger communication devices and integrated transceivers, as well as for two-way satellite messaging service from supported conventional mobile phones. The nearly polar orbit and communication between satellites via inter-satellite links provide global service availability.

The Iridium communications service was launched on November 1, 1998, formerly known as Iridium SSC. The first Iridium call was made from Vice President of the United States Al Gore to Gilbert Grosvenor, the great-grandson of Alexander Graham Bell and chairman of the National Geographic Society. Motorola provided the technology and major financial backing. The logo of the company represents the Big Dipper. The company derives its name from the chemical element iridium, which has an atomic number of 77, equaling the initial number of satellites which were calculated to be required for global coverage. However, due to optimizations of orbit trajectories, technology updates and real-world conditions, only 66 are required for global coverage. A total of 95 satellites were launched in this constellation, with 66 active and the remaining 29 satellites operating as spares.

On August 13, 1999, nine months after the launch of the organization, the founding company went into Chapter 11 bankruptcy. The handsets could not operate as promoted until the entire constellation of satellites was in place, requiring a massive initial capital cost of billions of dollars. The cost of service dissuaded many potential users. Reception indoors was difficult and the handheld devices, when compared to terrestrial cellular mobile phones were bulkier and more expensive, both of which discouraged adoption among potential users.

Mismanagement is another major factor that was cited in the original program's failure. In 1999, CNN writer David Rohde detailed how he applied for Iridium service and was sent information kits, but was never contacted by a sales representative. He encountered programming problems on Iridium's website, and a "run-around" from the company's representatives. After Iridium filed bankruptcy, it cited "difficulty gaining subscribers."

The initial commercial failure of Iridium had a damping effect on other proposed commercial satellite constellation projects, including Teledesic. Other schemes (Orbcomm, ICO Global Communications, and Globalstar) followed Iridium into bankruptcy protection, while a number of other proposed schemes were never even constructed.

In August 2000, Motorola announced that the Iridium satellites would have to be deorbited. Despite this, they remained in orbit and operational. In December 2000, the US government stepped in to save Iridium by providing US$72 million in exchange for a two-year contract. They also approved the fire sale of the company from US bankruptcy court for $25 million in March 2001. This erased over $4 billion in debt.

Iridium service was restarted in 2001, by the newly founded Iridium Satellite LLC, which was owned by a group of private investors.

On February 10, 2009, the Iridium 33 satellite collided with a defunct Russian satellite, named Kosmos 2251, 800 kilometres (500 mi) over Siberia. Two large debris clouds were created.