This chapter examines haptic user interfaces (HUIs), focusing on pin-array displays for braille and tactile graphics to enhance accessibility for visually impaired users. HUIs utilize both passive touch (sensing stimuli) and active touch (exploratory movement integrating kinesthetics) to improve user experience and support cognitive processes like reading. It details pin-array design (height, distance, force, and pattern-focused refresh) and “tactons” (tactile icons) as core elements. Braille, a vital global notation for text and complex information (math, music), is implemented via essential braille displays with input keys. HUIs fundamentally differ from visual/auditory interfaces due to the direct link between touch input and tactile output, creating design challenges for complex information on compact displays. Screen readers must maintain cross-modal coherence between graphical and haptic user interfaces, unlike other haptic user interfaces in this book. The chapter emphasizes haptic mock-ups (paper-based or modular) for early user testing, observing diverse exploration strategies, and identifying usability issues. Crucially, it explores retrieving users’ mental models of tactile interfaces, noting verbal descriptions’ limitations for spatial concepts and advocating non-verbal methods using tangible materials for accurate understanding. While braille displays are established successful HUIs, pin-array displays offer broader potential when designed for effective bi-manual exploration.