The principles of user interface design are intended to improve the quality of user interface design. According to Lucy Lockwood's approach of usage-centered design, these principles are:
According to Jef Raskin there are two laws of user interface design:
Additionally he mentions that "users should set the pace of an interaction", meaning that a user should not be kept waiting unnecessarily and that an interface should be monotonous with no surprises "the principle of monotony".