In the law of contracts, in order for a contract to be enforceable it must be supported by “consideration”. There must be some quid-pro-quo between the contracting parties.
The Latin phrase quid-pro-quo means literally “this for that” – signifying an exchange of one thing or performance for another. You work (labor) for money (payment). This is quid-pro-quo. A charitable gift on the other hand, involves “quid” but not “quo” – you give something but expect nothing in return (except perhaps a tax deduction. . .!) — Kevin Palmer