Lazy Loading
Lazy Loading is loading content only when it's needed—like images that load as you scroll to them, or code that loads when you navigate to a page.
Definition
Loading content only when it's needed—like images that load as you scroll to them, or code that loads when you navigate to a page.
Example
Images below the fold don't load until you scroll down, making the initial page load much faster.
Related Terms
More Web Development Terms
SSR - Server Side Rendering
The server builds the full HTML page before sending it to the browser. Great for SEO and fast initial loads because users see content immediately instead of a blank screen.
CSR - Client Side Rendering
The browser downloads a minimal HTML shell, then JavaScript builds the page. Fast subsequent navigations, but users might see a loading spinner on first visit.
Hydration
When server-rendered HTML gets "activated" by JavaScript in the browser. The page looks ready instantly, then becomes interactive once the JS loads and attaches event listeners.
SPA - Single Page Application
A web app that loads once and never does a full page refresh. Navigation feels instant because it just swaps content instead of requesting new HTML from the server.
MPA - Multi Page Application
The traditional web model where each page is a separate HTML document. Click a link, server sends a new page. Simple, reliable, and SEO-friendly out of the box.