Surface plasmon resonance (SPR) is used to monitor binding events between molecules ranging from ions to viruses. This technology provides binding, kinetics, affinity, specificity and concentration, without any needs for labels. Besides, SPR provides much more higher resolution of monitoring between biomolecules, comparing to traditional molecular experiments. It is a real-time detection, not an end-point reveal. It can make us better understand about the whole picture of molecular binding events and biological functions. Therefore, SPR is an indispensable technical service in the field of drug development.