The main role of saline is the following: first, saline is often used as a solute to dissolve other drugs, such as antibiotics, such as other injectable drugs, and through these as a lysozyme to function. For example, the vast majority of all infusion therapy is now used saline for dissolution, for infusion. Second, saline is mainly sodium chloride, sodium and chloride ions, mainly used in drugs, such as oral rehydration salts, etc., to replenish body fluids, and then maintain electrolyte balance. Thirdly, saline can be used externally for rinsing, such as after a wound trauma, saline for rinsing, to play the role of cleaning and sterilization or antibacterial.