What is money?
Money is a tool that helps transactions, so people do not need to rely on barter. This type of commerce is much more efficient than barter, because in the case of barter, two people need to meet, who need each other merchandise, which is difficult. If we have money in that case any person with money if finds a good or service that he wants, the transaction takes place.
That is why even in times where there was no actual money, some kind of asset emerged, accepted by almost everybody, for example cigarettes, chocolate or watches during the world wars.