A more thorough explanation:

Definition: A business establishment or place of employment. It can refer to a factory, office, or any other place of business.

There are different types of shops:

• Open shop: A shop in which the employer hires workers without regard to union affiliation.
• Union shop: A shop in which the employer may hire nonunion employees on the condition that they join a union within a specified time (usually at least 30 days).
• Closed shop: A shop in which the employer, by agreement with a union, hires and retains in employment only union members in good standing. Closed shops were made illegal under the federal Labor–Management Relations Act.
• Agency shop: A shop in which a union acts as an agent for the employees, regardless of their union membership. Nonunion members must pay union dues because it is presumed that any collective bargaining will benefit nonunion as well as union members.

For example, if a company is an open shop, it means that they do not require their employees to be part of a union. On the other hand, if a company is a union shop, they will only hire employees who are part of a union or who agree to join one within a certain period of time.

These different types of shops can have a big impact on the relationship between employers and employees, as well as on the power of labor unions.