Next.js
Also written as Nuxt.js, NextJS
A popular 'meta-framework' built on top of React that adds routing, server-side rendering, and other production features out of the box, so teams don't have to wire them up themselves. (Nuxt.js, Remix, and Astro play a similar role for Vue or other stacks.)
Think of it like
Like moving into a fully furnished apartment instead of an empty one — routing and server-rendering come pre-installed instead of you building each from scratch.
Junior or senior?
Junior sounds like
Has only built pages inside an already-configured Next.js project.
Senior sounds like
Has configured the rendering strategy themselves and can explain the choice.
Ask them
“Have you configured a Next.js app's rendering strategy yourself, or worked inside a project someone else set up?”