Interaction design is the design of behavior, positioned as dialogue between a person and an artifact. A person commonly doesn’t talk to an object; they use it, touch it, manipulate it, and control it. Usage, touching, manipulation and control are all dialogical acts, unspoken but conversational. Conversation is only a metaphor for interaction, but it’s a useful one. Many of the same ways we “read” an actual, spoken conversation have parallels in describing and discussing interactions between people and things.