Metabolomics is the general term for the study of the global metabolite composition of a biological system, the metabolome, under a given set of conditions. The investigation of the metabolome of a cell can be defined by a range of terms: metabolite profiling, metabolite fingerprinting, metabonomics, and metabolomics. Here, the term metabolite profiling is used to describe the rapid, but accurate quantification and identification of metabolites using a single analytical technique. Metabolite profiling is becoming increasingly important in all research areas. Its application ranges from diagnostics through gene function identification to systems biology.