A Definition of User Interface Design
Controls for interaction between people and products
User interface design is the practice of planning and shaping the form present between a product idea and its user, with particular focus on key interactive features or characteristics such as textures, shapes, knobs and buttons.
Information architecture or Interaction design are perhaps better approaches than User interface design for product ideation work because they stress more attention on the activity or function of a product. While the interface IS a critical component to the interaction, it is a product's function that directly responds to a user's goal and hence function should drive a product's form during design development. The user interface form should arise from the function and activity.

