NeXus (see NeXus website) is a new file format which in future should replace all binary and ASCII formats used to store data at synchrotron radiation facilities. Though virtually all synchrotron radiation facilities have agreed upon switching to NeXus using HDF5 as its underlying physical file format, the acceptance of NeXus among facility users and consequently the prevalence of the format is rather poor. There are many reasons for this rather unpleasant development but only a few of them are backed up by cautious technical arguments.
This chapter should give you a motivation why NeXus and HDF5 are important for the future of data acquisition and provide you with a short introduction to the underlying technologies and concepts. If you are new to NeXus and HDF5 it is strongly recommended that you read all the sections of this chapter before proceeding to the next chapters. NeXus and HDF5 in many ways change how we think about data storage today. The aim of this chapter is to convince you that both, NeXus as well as HDF5, are reasonable and superior technologies over technologies in comparison to what is in use today.