At its most basic, a job is a voluntary transaction between two entities — a buyer and a seller. It is a transaction that, when both parties live up to their expectations, betters both entities. The parties each agree to an exchange: the skill/talent/labor of the employee for the wealth/compensation of the employer, at a mutually agreed upon price. If it did not benefit each of them, they would not agree to the transaction. When the situation stops benefiting either party, either is free leave the relationship.