Polish labour law is mainly statutory law, while collective labour agreements play only a secondary role. The basic concepts are regulated by the Labour Code (LC). Under Article 2 LC, an employee is a person employed on the basis of an employment contract, an appointment, an election, a nomination, or a cooperative employment contract, while, according to Article 3 LC, an employer is an organizational unit, even if it has no legal personality, or an individual, provided it employs employees. Moreover, Article 22 § 1 LC provides that by establishing an employment relationship, an employee undertakes to perform specific work for the benefit and under the guidance of an employer, and an employer undertakes to employ an employee in return for remuneration. This definition is quite short and does not indicate all the features of an employment relationship. Those are – as determined by the jurisprudence and the legal literature – voluntary character, personal work performance on a continuous basis, subordination, and work performance for the benefit of an employer who carries the risk related to the employment. The legal nature of a contract cannot be determined on the basis of a single factor, only on a comprehensive assessment of the factual situation. There are three types of employment contract: a contract for a trial period, a fixed-term contract, and a contract for an indefinite period of time.