While making ice cream, why is salt added to the ice surrounding the ice-cream ingredients?

When you are making homemade ice cream, salt, also known as a sodium chloride, is needed to cause a freezing point depression. The freezing point depression is a colligative property, which occurs when the freezing point of the solvent is lowered. The salt causes a chemical reaction when put on top of ice or when mixed in to water, which is called dissociation separating the compound of salt (NaCl) into two ions Na+ and Cl-. Without the salt, the temperature of the ice would not be low enough to create ice cream. As salt lowers the freezing point, an endothermic reaction begins where the heat is absorbed and the new temperature of the liquid ice (water) is cold enough to freeze the ice cream. From then on, you'll begin to notice that the ice cream starts to form into a thick solution. The longer the low temperature ice is kept in contact of the bag of ice cream, the more the ice cream will slowly thicken. Before you know it, NaCl and ice together would be the assisting into creating a new substance. That phase of freezing which is from liquid to solid.