Wage labour (also wage labor in American English) is the socioeconomic relationship between a worker and an employer, where the worker sells their labour under a formal or informal employment contract. These transactions usually occur in a labour market where wages are market determined. In exchange for the wages paid, the work product generally becomes the undifferentiated property of the employer, except for special cases such as the vesting of intellectual property patents in the United States where patent rights are usually vested in the employee personally responsible for the invention. A wage labourer is a person whose primary means of income is from the selling of his or her labour in this way.