The contraction "won't" is a combination of the words "will" and "not." It is used to express refusal or the absence of willingness to do something in the future. For example, if someone says, "I won't go to the party," it means they have decided not to attend the event. In English grammar, "won't" is commonly used in both spoken and written language. It helps convey a clear message about intentions or decisions. For instance, a parent might say, "You won't eat dessert until you finish your dinner," indicating a condition that must be met.