The Internet, Servers & Deployment

What is a server?

You're building PetKarma on your laptop. You run the dev server. You open localhost:5000 in your browser. The app appears. Then you grab your tablet, connect to the same WiFi, type in a slightly different address, and the app appears there too.

Here's what was actually happening.

Your laptop in that moment was a server.

That's all a server is. A computer that is listening for requests and responding to them. Your laptop was listening. Your tablet made a request. Your laptop responded with the app.

The word "server" sounds like expensive mysterious hardware in a cold room somewhere. And sometimes it is that. But the concept is just a computer that listens and responds. That's it.

Your laptop was a local server. Local means only devices on the same network can reach it. Someone in another country couldn't reach it because they're not on your network.

What changes when you deploy?

When you deploy to Vercel — Vercel takes your app and puts it on their computers. Computers that are always on, always connected to the internet, and listening for requests from anyone in the world. Not just your WiFi. Anyone.

That's what "your app is on the internet" means. It means your app is now living on someone else's computer that never turns off and that the whole world can reach.

Vercel's computers are servers. Professional ones. In data centers. But doing the exact same job your laptop was doing at home. Listening and responding.

The full chain

You write code on your laptop → you push it to Vercel → Vercel puts it on their always-on computers → someone in Japan opens their browser → their browser makes a request to Vercel's computers → Vercel's computers respond with your app → the person in Japan sees PetKarma.

That's the whole internet in one chain.

Website vs. web app vs. program

People use these words interchangeably and they shouldn't. They're different things.

A website is mostly static. It's like a digital brochure. You go there, you read it, maybe click some links. It doesn't really change based on who you are. Content that doesn't change much. Fast to load. Simple.

A web app is dynamic. It changes based on who's using it and what they do. When you log in, it knows who you are. It shows your data. It responds to your actions. It has memory. PetKarma is a web app. Opsette is a web app.

A program (or application) runs directly on your device. Not in a browser. Microsoft Word. Spotify's desktop app. Your iPhone's camera app. These aren't websites at all. They're installed on the machine and talk directly to the hardware.