 The cluster mission was launched in 2000 as a cornerstone project of the European Space Agency, ESA, and is still operational today. Its main goal is to study small-scale plasma structures in key plasma regions, such as the solar wind, bow shock, magnetopause, polar cusps, magnetotail, and auroral zones. The mission plays a major role in the International Solar Terrestrial Program, ISTP, and has state-of-the-art plasma instrumentation to measure electric and magnetic fields from quasi-static up to high frequencies, and electron and ion distribution functions from energies of nearly zero EV to a fume EV. The science operations are coordinated by the Joint Science Operations Centre, JSOC, at the Rutherford Appleton Laboratory in the UK, and implemented by the European Space Operations Centre, ESOC, in Darmstadt, Germany. A network of eight national data centers has been set up for raw data processing, physical parameter production, and distribution to end users all over the world. This article was authored by C. P. Escobot, M. Ferringer, and M. Goldstein. We are article.tv, links in the description below.