Interfaces excel at one thing: enabling users to perform tasks without needing to understand the behind-the-scenes complexities. Flip a light switch, and you have light – without any electrical engineering expertise. The promise of simplicity and utility…that’s a good interface.
Interface disasters occur when that promise is broken. For example:
People have high expectations when using software or visiting a website. The Web 2.0 revolution has brought many innovations, like simplified graphics, contextual inline controls, direct-data manipulation (e.g. paging through photos on an iPhone) and global undo, all of which continue to be refined via web analytics and represent the future of human-machine interaction. So when designing an interface, use some common sense with icons and controls and basically stay out of the way of the user and their goals.