The largest percentage of the NIST dataset (60%) corresponds to metabolites (6K human metabolites and 8K plant metabolites) while a significant amount of the data is drugs (20%). The rest corresponds to peptides, lipids, forensics, surfactants/contaminants and sugars/glycans. The dataset contains low and high resolution MS/MS spectra, obtained through different fragmentation techniques. For a small number of molecules in the dataset there are available up to MS4 spectra. Each molecule in the dataset may be associated with more than one spectrum which may be obtained through different experimental conditions, that is, different fragmentation instrument, precursor ion, ionization mode, collision energy or fragmentation level (MS2, MS3 or MS4).