What is the term used for a person or firm that hires workers?

The term that refers to a person or firm that hires workers is "employer." This designation applies to any individual or organization that provides employment opportunities, typically overseeing the tasks and responsibilities of their employees while being responsible for compensating them for their labor. An employer establishes the terms of employment, including wages, benefits, and job duties.

In contrast, an employee is someone who works for the employer, providing labor in exchange for remuneration. A client typically refers to someone who receives services from a professional, often in a business-client relationship, rather than being involved in employment. A contractor may also hire workers but primarily refers to an individual or company contracted to perform a specific task or project, often without the same responsibilities that an employer has towards permanent employees. Thus, "employer" is the precise term that encapsulates the role of hiring and managing workers.