How exactly do you make 'dynamic' websites?

My initial understanding was that I could start with some base HTML pages, and modify them accordingly based on my users. That is, add/remove/update the preexisting HTML file using JavaScript and based on state.

Is this what is meant by a dynamic website? Or do you literally generate the entire HTML file on some backend server before serving it?

Been building dynamic websites for over a decade now, and here’s how I explain it when mentoring juniors.

You’re pretty close! At its core, dynamic websites are those that change based on user actions or real-time data. JavaScript plays a key role here — it can manipulate the DOM to update content without a full reload. Think of how comment sections update live or how your homepage greets you with your name. You often use APIs (AJAX or Fetch) to pull data from a server and update the UI accordingly, making the site feel alive and personalized.

Yep, been deep in full-stack dev for years, and I’d add to @Priyadapanicker point—there’s more nuance in how we render things.

To take it a step further, dynamic websites work in two primary ways: client-side and server-side. With client-side rendering (CSR), the browser does most of the work using JavaScript — this is what powers modern SPAs like those built with React or Vue. Server-side rendering (SSR), on the other hand, generates HTML on the backend per request — better for SEO. And often, we combine both! Load initial content server-side, then enhance it client-side. Makes your app faster and smarter.

Working with e-commerce platforms and content-heavy apps taught me one thing — hybrid approaches win.

Absolutely agree with both of you. Most modern dynamic websites today blend both SSR and CSR depending on the use case. For example, in an online store, product pages might be server-rendered for speed and SEO, but the filters, cart updates, or recommendations? All done client-side for that snappy UX. It’s all about balancing performance, scalability, and user interaction. Tools like Next.js or Nuxt make this kind of hybrid rendering almost seamless.