Interaction Design (IxD) is the discipline of defining the behavior of products and systems that a user can interact with. The practice typically centers around complex technology systems such as software, mobile devices, and other electronic devices. However, it can also apply to other types of products and services, and even organizations themselves. Interaction design defines the behavior (the "interaction") of an artifact or system in response to its users. Certain basic principles of cognitive psychology provide grounding for interaction design. These include mental models, mapping, interface metaphors, and affordances. Many of these are laid out in Donald Norman's influential book The Design of Everyday Things. Academic research in Human Computer Interaction (HCI) includes methods for describing and testing the usability of interacting with an interface, such as cognitive dimensions and the cognitive walkthrough.
