Data processing takes place constantly and everywhere in daily life. The interest in personal data is immense and will continue to rise. Increasingly strict data protection laws are often contrasted with a relatively careless handling of own personal data. This is often due to a lack of knowledge on the part of the persons concerned. This newsletter therefore describes the basic terms, concepts and principles of data protection and illustrates them with the practical example of a customer loyalty card. The example shows how many and manifold data processing operations can take place, where data protection law sets limits and when individuals should take action themselves.