Ionic liquids believed as novel chemical agents and widely regarded as a greener alternative to many commonly used solvents because they are designable, recyclable and non-volatile. Based on it, ionic liquids have been studied for a wide range of synthetic applications, they have attracted considerable interest for use as non-volatile solvent based electrolytes in the areas of organic synthesis, catalysis, electrochemistry, solar cells, fuel cells, etc., due to they possess many benefits than volatile organic solvent. Several studies indicate the successful of using simple chemical reactions to synthesize ILs for large-scale processes. Recently, five types of ionic liquids are attracted much attention specifically alkylation ionic liquids, metathesis ionic liquids, protic ionic liquids, eutectic ionic liquids and protic eutectic ionic liquids. For that reason, this study describes precursor, preparation and application of these ionic liquids.