View Transitions API

Headless UI refers to component libraries that provide behavior, state management, and accessibility logic without any predefined styling or markup. Libraries like Radix Primitives, Headless UI by Tailwind Labs, and React Aria give developers full control over visual presentation while handling complex patterns like focus management, keyboard navigation, and ARIA attributes. This approach decouples functionality from design, making it ideal for custom design systems.

Deep linking is the ability to direct users to a specific screen or content within a mobile or web application via a URL, rather than just opening the app's home screen. In React Native and Flutter, this involves configuring URL schemes (e.g., `myapp://profile/123`) or universal/app links that work across platforms. Deep linking is essential for push notification routing, marketing campaigns, sharing content between users, and creating seamless web-to-app transitions.

Memoization in React is a performance optimization that caches the result of expensive computations or component renders to avoid redundant work on re-renders. React provides `React.memo()` to skip re-rendering a component when its props haven't changed, `useMemo()` to cache computed values, and `useCallback()` to cache function references. While powerful, premature memoization adds complexity — it's best applied after profiling confirms an actual performance bottleneck.

JSX (JavaScript XML) is a syntax extension for JavaScript used primarily in React that lets you write HTML-like markup directly within your JavaScript code. It gets transpiled by tools like Babel or SWC into regular `React.createElement()` calls before reaching the browser. JSX supports embedding dynamic expressions with curly braces, conditional rendering, and mapping over arrays, making it a powerful and intuitive way to describe UI structures declaratively.

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.

Flutter is Google's open-source UI toolkit for building natively compiled applications for mobile, web, and desktop from a single Dart codebase. Unlike React Native which maps to platform-native UI components, Flutter renders everything with its own high-performance Skia/Impeller rendering engine, giving developers pixel-perfect control over every element on screen. This approach ensures identical visual output across platforms but means Flutter widgets don't automatically adopt platform-specific design conventions.