A flask is a container that keeps water hot. It is just as essential as a refrigerator. It has become an integral part of our daily life, both inside and outside the home. It allows us to enjoy hot water long after it has been boiled. It is an airtight container that keeps water warm by preserving heat using heat insulators all around the vessel. Besides keeping water warm and fresh for an extended period, it increases overall efficiency in our lives. You don't have to heat water repeatedly, which saves energy and fuel. By doing so, it also saves time and spares you from extra work.