PKD code (Polish Classification of Activities) is an element of the code system that was created to classify the types of economic activities carried out by enterprises and other organisational units in Poland. PKD codes are equivalent to the international NACE classification system. The system cooperates with other classification systems at European Union level. Each company or entrepreneur registering business activity in Poland must assign to its enterprise an appropriate PKD code, which corresponds to the main profile of its activity. PKD is organised in a hierarchical manner - from general categories to more detailed subcategories, which allows for the precise determination of the nature of the business conducted. PKD codes are used for various administrative and statistical purposes, including economic analysis, regional development planning or labour market monitoring. In addition, they are used in the licensing of certain activities and in state control and supervision systems.