ARIA

An affordance is a design property that suggests how an element should be used — a raised button looks clickable, a handle looks draggable, an underlined text looks like a link. In UI design, perceived affordances guide users toward correct interactions without explicit instructions. When affordances are missing or misleading (like text that looks clickable but isn't), users experience confusion and frustration.

Internationalization (i18n) is the process of designing software so it can be adapted to different languages, regions, and cultures without code changes. This involves externalizing strings, supporting right-to-left (RTL) layouts, handling date/number/currency formatting, and accommodating text expansion. Libraries like react-intl, next-intl, and i18next provide the infrastructure for managing translations and locale-aware formatting in JavaScript applications.

Server-Side Rendering (SSR) is a technique where web pages are rendered to HTML on the server for each request, rather than relying on client-side JavaScript to build the page in the browser. SSR provides faster initial page loads and better SEO since search engines receive complete HTML content. Modern SSR in frameworks like Next.js supports streaming, allowing the server to progressively send HTML chunks as they become ready rather than waiting for the entire page to render.

CSS Grid is a two-dimensional layout system that lets you define rows and columns simultaneously, making it ideal for complex page layouts. Unlike Flexbox which works in one axis at a time, Grid allows you to place items precisely in both horizontal and vertical directions using named areas or line numbers. Features like `grid-template-areas`, `auto-fill`, and `minmax()` make it possible to create responsive layouts with minimal code.

React Server Components (RSC) are components that render exclusively on the server and send only their HTML output to the client, with zero JavaScript bundle impact. They can directly access databases, file systems, and backend services without API endpoints. Combined with Client Components (marked with `'use client'`), RSC enables a hybrid architecture where interactive parts ship JavaScript while static or data-heavy parts remain server-only. Next.js App Router uses RSC as its default component model.

Responsive design is an approach to web development where layouts, images, and UI elements adapt fluidly to different screen sizes and devices. It relies on flexible grids, media queries, and relative units like `rem`, `%`, and `vw` to ensure a consistent experience from mobile phones to large monitors. Modern responsive design increasingly uses CSS Container Queries and intrinsic sizing techniques to create components that respond to their own container rather than the viewport.