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Web applications

Overview​

A web application is software accessed through a browser (or webview) that often provides interactive, stateful experiences: accounts, dashboards, forms with validation, real-time updates, and integrations with APIs. Unlike a mostly static marketing site, web apps emphasize application logic, data, and auth.

Key concepts​

  • Client vs server — UI in the browser; business rules and secrets on the server.
  • SPAs & MPAs — Single-page apps (e.g. React router) vs multi-page server-rendered flows.
  • APIs — REST, GraphQL, or RPC between client and backend services.
  • Authentication & sessions — Cookies, JWTs, OAuth, and secure storage patterns.
  • State & caching — Client stores, service workers, CDN and HTTP caching.

Request flow (simplified)​

Sample: fetch JSON from an API​

async function loadProfile(userId) {
  const res = await fetch(`/api/users/${userId}`, {
    headers: { Accept: 'application/json' },
  });
  if (!res.ok) throw new Error(`HTTP ${res.status}`);
  return res.json();
}

References​