A

• A/B TestingAn A/B test is an experiment that shows two versions of a page or element at the same time to randomly split groups of visitors. It lets you decide with real data which version works better.
• ARIAARIA is a W3C standard that adds roles, states and properties to HTML. It tells screen readers what an element is and how it currently behaves.
• AccessibilityAccessibility means designing websites, apps and digital documents so that everyone can use them, including people with visual, hearing, motor or cognitive disabilities.
• AffordanceAn affordance describes what action an object makes possible and whether people can recognize it: a button invites you to press it, a handle invites you to pull.
• Alt TextAlt text is a short text version of an image, stored in the HTML alt attribute. Screen readers read it aloud so people who can’t see the image get the same information.
• Atomic DesignAtomic Design is a method for building user interfaces from small, reusable building blocks, from single elements like buttons all the way up to complete pages.

B

• BFSGThe BFSG, Germany’s Accessibility Strengthening Act, has required many companies since 28 June 2025 to make certain products and digital services, such as online shops, accessible.

C

• Card SortingCard sorting is a research method in which people sort terms written on cards into groups. It shows you how they mentally organize content, so you can plan navigation that makes sense to them.
• Cognitive LoadCognitive load is the mental effort it takes to understand and use an interface. The less unnecessary thinking a design demands, the easier the actual task becomes.
• Color Vision DeficiencyA color vision deficiency means someone has a harder time telling certain colors apart than most people. The most common type is red-green deficiency.
• Contextual InquiryContextual inquiry is a research method where you observe and interview people in their real work environment. It shows you how they actually get tasks done, not just how they describe it.
• Contrast RatioThe contrast ratio describes how much two colors differ in brightness, such as text and background. WCAG requires at least 4.5:1 for normal text.
• ConversionA conversion is a desired action on a website or in an app, such as a purchase or a signup. The conversion rate shows what share of visits leads to one.

D

• Dark PatternsDark patterns are design tricks that push people into decisions they don’t actually want to make, like hidden cancellation options or preselected add-ons.
• Design SystemA design system is a shared toolkit of reusable building blocks and rules. It helps teams design and build interfaces that look and behave consistently everywhere.
• Design ThinkingDesign thinking is an approach that helps teams understand a problem from the perspective of the people affected and then develop, try out and improve solutions in quick loops.
• Double DiamondThe Double Diamond is a process model from the UK Design Council. It splits design work into four phases and shows when a team should think broadly and when it should commit.

E

• Easy LanguageEasy Language (Leichte Sprache) is a highly simplified form of German that follows fixed rules. It makes texts understandable, above all for people with learning disabilities.
• Empty StateAn empty state is a place in an application where there is currently no content to show, such as an empty list or a search with no results. Done well, it explains what belongs there and shows the next step.
• Eye TrackingEye tracking measures where people look on a screen, for how long and in what order. It shows you what gets noticed and what gets missed.

F

• Fitts’ LawFitts’ Law describes how long it takes to hit a target with a movement: the bigger and closer the target, the faster and more reliably you reach it. In UX design, it helps you size and place buttons and links.

G

• Gestalt PrinciplesThe Gestalt principles describe how your brain automatically groups individual elements into wholes and shapes. In design, they help you structure layouts clearly without extra lines or borders.

H

• Hamburger MenuThe hamburger menu is an icon made of three horizontal lines that hides the navigation of a website or app. It saves space but makes content harder to find.
• HeatmapA heatmap uses color to show where people click, scroll or move the mouse on a website. It reveals what visitors do, but not why they do it.
• Heuristic EvaluationIn a heuristic evaluation, experts review an interface against established rules of thumb for good usability. It helps you find typical weak spots quickly and cheaply, even before real people test the product.
• Hick’s LawHick’s Law states that decisions take longer the more equally likely options there are. Decision time grows much more slowly than the number of options, though.
• Human-Centered DesignHuman-centered design is an approach in which people, their tasks and their environment shape the entire development process. The standard ISO 9241-210 describes it with six principles.

I

• Information ArchitectureInformation architecture describes how the content of a website or app is structured and labeled. It helps people find what they’re looking for and understand where they are.
• Information ScentInformation scent describes how well people can judge from cues like link text whether a click will lead them to what they are looking for.

J

• Jakob’s LawJakob’s Law states that people spend most of their time on other websites, so they expect yours to work the same way as the ones they already know.
• Jobs to be DoneJobs to be Done is a way of thinking that asks what task people want to get done with a product and what progress they’re trying to make in their situation. It focuses on context and motivation rather than traits like age or job title.
• Journey MapA journey map shows step by step what a person experiences, thinks and feels while working toward a goal with a product or service. It reveals weak spots across channels and departments.

K

• Keyboard AccessibilityKeyboard accessibility means a website or app can be used entirely without a mouse. For many disabled people, it’s what makes a product usable in the first place.

L

• Lean UXLean UX is a way of working in which teams turn assumptions into hypotheses and test them with small experiments. Shared learning replaces heavy documentation.

M

• Mental ModelA mental model is the idea people form of how something works. It’s based on experience and assumptions, not on how the system actually works under the hood.
• MicrocopyMicrocopy is the short text in an interface, such as button labels, hints and error messages. It answers people’s questions at the exact moment they come up.
• MicrointeractionsMicrointeractions are small, self-contained moments in a product that do exactly one thing, like a like button or a toggle, and show you right away what just happened.
• Miller’s LawMiller’s Law describes the observation that people can only hold a small number of information units in short-term memory at once. Miller suggested about seven in 1956; newer research points to about four.
• Minimum Viable ProductA minimum viable product (MVP) is the smallest usable version of a product. It lets you test with as little effort as possible whether real people actually want your idea.
• MockupA mockup is a static, visually detailed design of a website or app. It shows what the finished product should look like, but you can’t interact with it yet.

N

• NudgingNudging means gently steering people in one direction by how a choice is designed, without forbidding options or noticeably changing their incentives.

O

• OnboardingOnboarding is how new users get started with a product. Good onboarding gets people to their first real success as quickly as possible instead of explaining every feature up front.

P

• PersonaA persona is a fictional person, grounded in real research, who represents a typical group of users. It helps teams make decisions from those people’s point of view.
• Priming EffectThe priming effect describes how an earlier stimulus shapes how quickly or in which direction you perceive and interpret a later one, usually without you noticing.
• Progressive DisclosureProgressive disclosure is a design principle where an interface shows only the essentials at first. More options and details appear only when someone asks for them.
• PrototypeA prototype is an early, testable model of a product. It lets you check ideas with real people before time and money go into development.

S

• Screen ReaderA screen reader is software that reads screen content aloud or outputs it on a braille display. Many blind and low-vision people use one to operate their computer and phone.
• SignifierA signifier is a perceivable cue that shows what you can do with an element and where, like a “Pull” sign on a door or a button with a clear shape.
• System Usability ScaleThe System Usability Scale (SUS) is a short, standardized questionnaire with ten statements. It sums up how usable people perceive a product to be as a single score from 0 to 100.

T

• Tree TestingTree testing is a research method for checking whether people can find content in a navigation structure. Only the outline of labels is tested, with no visual design at all.

U

• UX WritingUX writing is the craft of writing the words that guide people through a digital product, such as buttons, hints and error messages. The goal is that every task works without guesswork.
• UsabilityUsability describes how well people can use a product to reach their goal: effectively, without unnecessary effort and with a good feeling.
• Usability TestingIn usability testing, real people complete typical tasks with a product while you watch where they hesitate or fail. It helps you find problems before they frustrate your customers.
• User ExperienceUser experience (UX) covers everything people perceive and feel before, during and after using a product or service. Usability is one part of it.
• User ResearchUser research is the systematic study of the people who use a product: their goals, their behavior and their context. It gives you a foundation for design decisions based on evidence instead of guesswork.

W

• WCAGWCAG (Web Content Accessibility Guidelines) are the W3C’s internationally recognized guidelines for accessible web content. They define testable criteria that laws around the world build on.
• WireframeA wireframe is a schematic floor plan of a page or screen. It shows which content and controls go where, deliberately without colors, fonts or images.
• Working MemoryWorking memory holds information for a short time so you can work with it. It has very little capacity, so interfaces should ask people to remember as little as possible.