Author and founder of Adaptive Path — a user experience consultancy, Jesse James Garrett, defines interface design as being all about selecting the right interface elements — like text, buttons, text fields, color coded lists, etc — for the task the user is trying to accomplish and arranging them on the screen in a way that will be readily understood and easily used. The goal is to make the user’s interaction as efficient and simple as possible.
Interface elements include but are not limited to:
Input Controls: buttons, text fields, checkboxes, radio buttons, dropdown lists, list boxes, toggles, date field
Navigational Components: breadcrumb, slider, search field, pagination, slider, tags, icons
Informational Components: tooltips, icons, progress bar, notifications, message boxes, modal windows
Tools of the trade: Photoshop, Sketch, Illustrator, Fireworks, InVision