Individualization is used in a wide variety of ways to enhance applications both for users and for branding of the applications themselves. The wide variety of different implementations includes many instances where individualization creates considerable challenges for the very users that it ought to be helping. This becomes an even greater challenge when users have to deal with different individualization approaches in each of the several applications that they use. The purpose of DIN EN ISO 9241-129 is to provide guidance on the application of software individualization in order to achieve as high a level of usability as possible. Thus, it deals with individualization as the modification of interaction and presentation of information to suit individual capabilities and needs of users. Individualization enables support of a wide range of users, tasks, and contexts of use. It is particularly useful in increasing accessibility. This standard goes beyond the scope DIN EN ISO 9241-11 and describes, in addition to the general guidance on individualization, more details on the ergonomic use. DIN EN ISO 9241-129 deals with both user-initiated and system-initiated individualization. It encompasses the concepts of configuration, customization, adaptivity, adaptation, profiling, and internationalization. It serves the following types of users: - designers of user-interface development tools and style guides to be used by interface designers; - user-interface designers, who will apply the guidance during the development process; - developers, who will apply the guidance during the design and implementation of system functionality; - system administrators responsible for implementing solutions to meet end-user needs; - buyers, who will reference DIN EN ISO 9241-129 during product procurement; - evaluators, who are responsible for ensuring that products are in accordance with the recommendations of DIN EN ISO 9241-129. The ultimate beneficiary of DIN EN ISO 9241-129 will be the end-user of the software. Although it is unlikely that end-users will read DIN EN ISO 9241-129, its application by designers, developers, buyers and evaluators ought to provide user interfaces that are more usable through the use of individualization. DIN EN ISO 9241-129 deals with the development of software for user interfaces. However, anyone involved in designing the hardware aspects of user interfaces may also find it useful when considering the interactions between software and hardware aspects.