The principle of security means the actual protection of data by technical and organisational measures. These measures guarantee the confidentiality, availability, integrity and authenticity of the data as well as the traceability of data processing. Here too, the principle of proportionality applies and the measures must correspond to the state of the art. The more sensitive the data to be protected, the higher the requirements for this data protection. Since the human being is regularly the weakest link in the chain of data protection, not only technical but also organisational measures are important. The traceability of data processing requires appropriate logging. Both of these are also the focal points of the new EU General Data Protection Regulation (GDPR) explained below.