The ionic liquids are very important solvents in chemical science. These are termed as melts, designer solvents, electrolytes, ionic glasses, fused salts, ionic fluid, and green solvents. The ionic liquids are being used in the different research and industrial areas of chemical science. The most important applications of the ionic liquids in the chemical science include extraction, separation, electro-analysis and spectroscopic studies. This chapter describes the utility of the ionic liquids in the chemical science. Besides, the efforts were made to highlight the toxicity and future of the ionic liquids.