In contrast to other efforts in the PGAS community, GASPI is neither a new language (like e.g. Chapel from Cray), nor an extension to a language (like e.g. Co-Array Fortran). Instead — very much in the spirit of MPI — it complements existing languages like C/C++ or Fortran with a PGAS API which enables the application to leverage the concept of the Partitioned Global Address Space. In contrast to, for example, OpenShmem or Global Arrays, GASPI is not limited to a single memory model, but provides configurable and yet globally accessible memory segments. GASPI is interoperable with MPI and allows for incremental porting of legacy applications.