A web application that loads once and then redraws the interface in the browser as the user navigates, instead of requesting a new page from the server on every click.
SPAs feel instant and suit dashboards, editors, and admin panels where the user stays inside one tool for a long session. The trade is a heavier first load and extra work to stay visible to search engines.
We use SPA behaviour for product interfaces behind a login and server-rendered pages for public content, combining both in one Next.js codebase rather than choosing one style for the whole product.