In addition to the data protection principles already considered, the GDPR defines a number of rights for data subjects, i.e. the persons whose data are processed. These rights include the right to information and the right to rectification or erasure of data. In order to implement these rights, a software system must provide certain functionalities. For example, it must be possible to find data about a specific person in unstructured data collectionsUnstructured data in order to provide information about the data processed, to correct it or to delete it. This chapter describes the importance of data subjects’ rights for software development and IT, including the requirements for software to be developed resulting from these rights, taking into account that these partially overlap with the requirements resulting from the principles.