A cooler is an insulated box, used to keep food or drink cool. Ice cubes are most commonly put in on top of the items, filling in between them. Ice packs are sometimes used, as they either contain the melting water inside, or have a gel sealed inside that also stays cold longer than plain water. Coolers are often taken on picnics, and on vacation or holiday. Where summers are hot, they may also be used just for getting cold groceries home from the store, such as keeping ice cream from melting in a hot car. Even without adding ice, this can be a big help, particularly if having to make another brief stop on the way home.