What Next.js actually means for your website
If you've received a proposal from a web agency in the last two years, there's a reasonable chance it mentioned Next.js. Most proposals don't explain what it is or why it matters. This is a plain-language explanation for clients who want to understand what they're agreeing to.
The short version
Next.js is a framework for building websites and web applications using React, a widely-used JavaScript library. It handles a lot of the technical infrastructure that would otherwise need to be built from scratch: routing, image optimisation, server-side rendering, and deployment configuration.
For you as a client, the main practical effects are page speed and maintainability. Sites built in Next.js tend to load quickly because pages are pre-rendered where possible, and the framework has built-in tools for optimising images and fonts. The code is also structured in a way that most modern developers can read and extend without a lengthy handover.
Why it's become a common choice
A few years ago, the standard approach for a marketing site was WordPress. It's still a reasonable choice for certain projects, particularly those with complex publishing workflows or a large existing content library. But WordPress sites require ongoing maintenance: plugin updates, security patches, and occasional conflicts between plugins that break things unexpectedly.
Next.js sites have fewer moving parts. There's no plugin ecosystem to maintain, and the hosting options (Vercel and Netlify are the most common) handle infrastructure automatically. For a small business that doesn't have a developer on staff, fewer moving parts usually means fewer problems.
What it doesn't do
Next.js is a development framework, not a design tool and not a CMS. It doesn't determine what your site looks like or how easy it is to edit content. Those decisions are made separately. A Next.js site can be paired with any headless CMS, or with no CMS at all if the content rarely changes.
It's also worth knowing that Next.js is maintained by Vercel, a commercial company. The framework is open source and widely used, but it's worth understanding that dependency when making a long-term technology decision.
Most clients don't need to understand Next.js in depth. But knowing roughly what it is makes it easier to ask the right questions when reviewing a proposal.