ion-abundant liquid media is their huge potential to be fine-tuned. Thus, one can design an ionic liquid with virtually any combination of physicochemical or biochemical properties. Research in the area of “liquid ions” is a rapidly developing scientific field, and numerous data on their properties and activities have been accumulated so far. Currently, the concept finds applications in catalysis, electrochemistry, analytics, fuel production, biomass processing, biotechnology, biochemistry and pharmaceutics. References Biochemistry Ions Chemistry Omics