An increasing number of studies, in a wide range of disciplines, make use of so-called linked employer-employee databases. These detailed databases are only available in a limited number of countries. Denmark is one of the countries that makes this data available to researchers that are connected to a Danish research institute. Due to the sensitivity of the data, access is only granted after a thorough screening process and under strict conditions. Nevertheless, there is an international interest in the structure of this database and what information it provides. The purpose of this document is to provide such an description in English.