What is it that lives if it is fed, and dies if you give it a drink?

(This should be really easy)

Fire is it that lives if it is fed, and dies if you give it a drink.

Explanation:

Fire is very essential part of human life. It is used for cooking food and for other important activities. Without fire we cannot not survive. Something or the other should be heated before consumption and this can be achieved only with fir. It is also used in the darker places for viewing many things around us.

Thus, fire can survive if we give fuel or any wooden pieces and when water is poured on it it will turn off. Hence Fire is the one that survives when it is fed and dies when water is given as a drink to it.