That is the meaning of the word "free", though: no charge for the exchange. A store gives a "free sample" of cheese, for example, when they offer pieces of chee

That is the meaning of the word "free", though: no charge for the exchange. A store gives a "free sample" of cheese, for example, when they offer pieces of cheese to customers without charging them. The Dropbox "free tier" gives you a certain amount of storage space "for free", i.e. without you having to pay a fee. It does not imply that the cheese or the storage space materialized out of thin air without using anyone's resources.