Dictionary

Chain of Thought (CoT) is a prompting technique that encourages an LLM to break down complex reasoning into intermediate steps before arriving at a final answer. By explicitly reasoning through each step, models achieve significantly better accuracy on math, logic, and multi-step problems. Extended thinking and "thinking" tokens in models like Claude represent a built-in form of chain-of-thought reasoning.

Code splitting is an optimization technique that breaks a JavaScript bundle into smaller chunks that are loaded on demand, rather than forcing users to download the entire application upfront. In React, this is achieved through `React.lazy()` and dynamic `import()` statements, which create separate bundles loaded only when the corresponding component or route is accessed. This dramatically improves initial load times, especially for large single-page applications with many routes.

Cognitive load refers to the amount of mental effort required to use an interface. In UX design, reducing cognitive load means simplifying choices, minimizing distractions, and presenting information progressively so users aren't overwhelmed. Techniques like consistent layouts, clear visual hierarchy, familiar patterns, and sensible defaults all help keep cognitive load manageable and allow users to focus on their actual tasks.

Color contrast is the measurable difference in luminance between foreground text (or UI elements) and their background. WCAG guidelines require a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text to ensure readability for users with visual impairments. Tools like Chrome DevTools, Stark, and WebAIM's contrast checker help developers verify compliance during development.

A component library is a curated set of pre-built, reusable UI elements — buttons, inputs, modals, cards — packaged for consistent use across projects. Libraries like Material UI, Chakra UI, or Radix provide accessible, themeable building blocks so developers don't have to reinvent common patterns. A well-maintained component library drastically reduces development time and ensures visual consistency throughout an application.

Computer vision is a field of AI that trains machines to interpret and understand visual information from images and videos. Applications include object detection, facial recognition, autonomous driving, and medical image analysis. Modern computer vision leverages deep learning models like CNNs and vision transformers (ViT), and increasingly integrates with language models in multimodal AI systems.

Container Queries allow CSS styles to respond to the size of a parent container rather than the browser viewport, solving a long-standing limitation of media queries. By marking an element as a containment context with `container-type`, its children can use `@container` rules to adapt their layout based on the container's dimensions. This makes truly reusable components possible — a card component can rearrange itself whether it's in a sidebar or a full-width section.

React's Context API provides a way to pass data through the component tree without manually threading props through every intermediate level. You create a context with `createContext`, wrap a subtree with a `Provider`, and consume the value anywhere below with `useContext`. It's ideal for global concerns like themes, authentication state, or locale, but should be used judiciously since any change to context value re-renders all consuming components.

A context window is the maximum amount of text (measured in tokens) that an LLM can process in a single interaction, encompassing both the input prompt and the generated output. Larger context windows allow models to handle longer documents, maintain extended conversations, and reason over more information at once. Context window sizes have grown rapidly — from 4K tokens in early GPT models to over 1M tokens in current models like Claude.

A controlled component is a form element in React whose value is driven by React state rather than the DOM's own internal state. The component's value is set through a `value` prop and updated via an `onChange` handler, giving React full control over the form data. This pattern enables validation on every keystroke, conditional disabling of submit buttons, and enforcing input formats, making it the recommended approach for most form handling in React applications.

Cross-platform development is the practice of building applications that run on multiple operating systems (iOS, Android, web, desktop) from a single codebase. Frameworks like React Native, Flutter, and Kotlin Multiplatform each take different approaches — from shared UI rendering to shared business logic with native UI. The key trade-off is between code reuse efficiency and the ability to deliver platform-native experiences that feel right on each device.

Dark mode is a UI color scheme that uses light-colored text and elements on a dark background. It reduces eye strain in low-light environments, can save battery on OLED screens, and has become an expected feature in modern applications. Implementation typically involves CSS custom properties or design tokens that switch between light and dark theme values, often respecting the user's system-level preference via the `prefers-color-scheme` media query.