Human-Computer Interaction

Designing software that people with diverse abilities — visual, auditory, motor, cognitive — can use effectively.

A text-based user interface where you type commands and read text output — small, fast, scriptable, and the default for system administration and development.

A user interface built from visual elements you point at and manipulate — windows, icons, menus, pointers — as opposed to typing commands.

The surface where a person and a computer meet — what users see, touch, hear, and act on.

The discipline of shaping how a person feels and what they can do when using a product, system, or service.

A key combination that triggers a command directly, letting experienced users work faster than navigating menus — a classic trade-off between discoverability and efficiency.

An interface operated by touching the screen directly with fingers — using taps, swipes, and gestures instead of a mouse and keyboard — the dominant way people interact with phones and tablets.

Watching real people attempt real tasks with a product to discover where they struggle — the most direct way to find out whether a design actually works.

A shared, documented set of reusable UI components, patterns, and guidelines that keeps a product's interface consistent and lets teams build faster.

User interface designs that trick, confuse, or coerce users into unintended actions — subscribing to services, sharing data, or making purchases they did not intend — through deliberate manipulation of attention and decision-making.

A set of perceptual principles from 1920s psychology describing how humans group visual elements — proximity, similarity, closure, continuity, and figure-ground — foundational to visual UI design.

A predictive model of human pointing performance — time to acquire a target depends on the distance to the target and its size, expressed as T = a + b·log₂(2D/W) — guiding the design of interactive UI elements.