What are Design Principles?
Design principles are sets of generally applicable laws, guidelines, human biases, and design considerations, all of which reflect the accumulated knowledge and experience of practitioners and researchers. They serve as a starting point for the creation of new designs to solve problems. Design principles usually combine developments across all design-related disciplines, including behavioral science, sociology, physics, and ergonomics.
According to William Lidwell, Kritina Holden, and Jill Butler, authors of the book Universal Principles of Design, design principles are aimed at helping designers find ways to enhance usability, influence perception, increase appeal, teach users, and make sound design decisions during projects. The careful selection and application of appropriate principles should increase the probability that a design will be successful. Although these principles have general applicability, the choice of which to apply to a project is usually left to the designer’s critical ability. Additionally, the way in which the designer can apply each principle also heavily depends on his or her ability to rationalize, understand, and contextualize the problems he or she has been called upon to solve. Therefore, successfully applying such principles takes a keen eye and skill at making judgment calls on users’ perceptions and likely actions—attributes of a designer that tend to improve with experience in the field.
To help designers gain inspiration for implementing a particular principle, “guidelines” (i.e., practical information on how to implement a principle) come into play. A design guideline (e.g., “text should be easy to read”) sits between a principle in design (e.g., “an interface should be easy to use”) and a standard or rule for implementing it (e.g., “background: white; font-color: black; font-size: 20px”). A design principle thus reflects a philosophy or aim of design, whereas a guideline is intended to help designers understand how to implement a principle.