Design
Design is the creation of a plan or convention for the construction of an object, system or measurable human interaction (as in architectural blueprints, engineering drawings, business processes, circuit diagrams, and sewing patterns). Design has different connotations in different fields (see design disciplines below). In some cases, the direct construction of an object (as in pottery, engineering, management, coding, and graphic design) is also considered to use design thinking.
Interaction
Interaction is a kind of action that occur as two or more objects have an effect upon one another. The idea of a two-way effect is essential in the concept of interaction, as opposed to a one-way causal effect. A closely related term is interconnectivity, which deals with the interactions of interactions within systems: combinations of many simple interactions can lead to surprising emergent phenomena. Interaction has different tailored meanings in various sciences. Changes can also involve interaction.
Interaction Design
Interaction design, often abbreviated as IxD, is "the practice of designing interactive digital products, environments, systems, and services." Beyond the digital aspect, interaction design is also useful when creating physical (non-digital) products, exploring how a user might interact with it. Common topics of interaction design include design, human–computer interaction, and software development. While interaction design has an interest in form (similar to other design fields), its main area of focus rests on behavior. Rather than analyzing how things are, interaction design synthesizes and imagines things as they could be. This element of interaction design is what characterizes IxD as a design field as opposed to a science or engineering field.
Design
One of the best ways to economize in building is to economize on ugliness. ...Nothing can be greater service in avoiding ugliness than a knowledge of the principles of design.
Ernest Flagg, Small Houses: Their Economic Design and Construction (1922)
Design
This is exactly the meaning of design: the conflict between form and content, form being the problem. [...] It is the coming together of form and content that is the realization of design.
Paul Rand (2008), Conversations with Students p. 32
Design
Good design is a Renaissance attitude that combines technology, cognitive science, human need and beauty to produce something.
Paola Antonelli (2001), curator of architecture and design, Museum of Modern Art, New York, in A Conversation About The Good, The Bad And The Ugly