Interaction design (IxD) is "the practice of designing interactive digital products, environments, systems, and services."Like many other design fields Interaction Design also has an interest in form but its main focus is on behaviour. What clearly marks Interaction design as a design field as opposed to a science or engineering field is that it is synthesis and imagining things as they might be, more so than focusing on how things are.
Interaction design is heavily focused on satisfying the needs and desires of the people who will use the product. Where other disciplines like software engineering have a heavy focus on designing for technical stakeholders of a project.