Hydration

Hydration is the process of restoring client-side interactivity to a server-rendered HTML page by reattaching JavaScript event listeners and state to the DOM. In server-side rendering (SSR), the server sends a fully rendered HTML page to the browser, which is immediately visible to the user. Hydration then allows JavaScript to take over, enabling dynamic interactions on the page.

This approach improves perceived performance by showing content quickly while deferring the full execution of JavaScript until after the initial render.