Interaction Design (IxD) is a professional discipline of creating digital products with a focus on how user will interact with them.

“Interaction Design is the creation of a dialogue between a person and a product, system, or service. This dialogue is both physical and emotional in nature and is manifested in the interplay between form, function, and technology as experienced over time.”

John Kolko (Thoughts on Interaction Design)

In modern design industry the lines between Interaction Design, UX Design, and Interface Design are often blurred. It is common to see a UX/UI Designer role that is responsible for all aspects of design, including IxD. One important distinction is that interaction designers often work on no-UI systems, for example, voice user interfaces (such as Google Home, and Amazon Alexa).