boiling means matter / a substance changes from a liquid into a gas by increasing heat energy & water is a kind of substance ->  water boiling is when water changes from a liquid into a gas  water boiling is when water changes from a liquid into a gas & water is in the liquid state , called liquid water , for temperatures between 0 c and 100 c & water is in the gas state , called water vapor / steam, for temperatures above 100 c -> water boiling is when water changes from liquid water to water vapor