There are many things that can be heated. First of all, people can heat their homes if it is cold. But even if it is not cold, then there are various reasons why a person would want to heat water in his house. In such a case, he might need a tankless water heater or other ways to heat water. Washing hands in hot water is very hygienic and it should be done even if it is not cold outside. People should take care of their health and one of the basic ways to do that is to make sure that whatever you do is hygienic. That is also something that should be taught to children.