Book excerpt: Designing User Interfaces for an Aging Population: Towards Universal Design presents age-friendly design guidelines that are well-established, agreed-upon, research-based, actionable, and applicable across a variety of modern technology platforms. The book offers guidance for product engineers, designers, or students who want to produce technological products and online services that can be easily and successfully used by older adults and other populations. It presents typical age-related characteristics, addressing vision and visual design, hand-eye coordination and ergonomics, hearing and sound, speech and comprehension, navigation, focus, cognition, attention, learning, memory, content and writing, attitude and affect, and general accessibility. The authors explore characteristics of aging via realistic personas which demonstrate the impact of design decisions on actual users over age 55. - Presents the characteristics of older adults that can hinder use of technology - Provides guidelines for designing technology that can be used by older adults and younger people - Review real-world examples of designs that implement the guidelines and the designs that violate them