The publication contains characteristics of the REGON register - basic terms and definitions used in the register and description of data groupings, as well as analytical commentary enriched with information regarding corporate services sector. Moreover, the elaboration is complemented by a set of tables in the form of Excel files, divided into two parts. The first part includes review tables, in which retrospective layout spanning the year 2010 was used. The second part consists of detailed tables, presenting the number and structure of entities as of the end of 2017 in comparison with the previous year.