IMAGINARY is a platform for open and interactive mathematics. It features a variety of content that can be used in schools, at home, in museums, at exhibitions or for events and media activities. The main contents of IMAGINARY are its interactive programs and its picture galleries. The platform allows an easy integration of new content, for example of additional mathematical subjects or exhibitions. One main goal of IMAGINARY is to enable you, the community, to participate and to get involved with your own ideas. The core idea is that exhibits are created within the community and exhibitions are organized independently. This concept and the platform grew from our initial IMAGINARY exhibition, which started in 2008 and has since then been shown in more than 140 cities all around the world. Its huge success and its growing community led to the creation of this platform! IMAGINARY is a non-profit organisation for interactive and open mathematics (IMAGINARY gGmbH). It was initiated at the Mathematisches Forschungsinstitut Oberwolfach (MFO), an institute of the Leibniz Association. The MFO is a shareholder of IMAGINARY.