In this publication, political parties are presented as central institutions of modern democracy. The characteristics and functions of parties, the basic elements of their organisation, their political and social context, as well as the problems of party democracy and the specific challenges faced by parties are the main topics. This is to convey fundamental information on the different facets of political parties. At the same time, it is meant to raise interest in, and willingness to contribute to, a party. Even though criticism of political parties is easy and always popular, political parties are indispensable for democracy. They will only be able to fulfill their functions when more citizens are willing to engage politically in parties.