What Is a Server? A Plain-English Explanation

"It runs on a server." "The server is down." "You'll need a server for that." The word comes up constantly when you build apps, and it's used for at least three different things. Here's what it actually means.

The one-sentence answer

A server is a computer (or a program on a computer) that waits for requests and answers them.

That's it. Your laptop asks for a web page; a server somewhere serves it. The name describes the job, not the hardware.

Three meanings of "server"

1. The machine. A computer, usually in a data centre, that's always on and connected to the internet. It has a processor, memory, and storage, just like your laptop — often much more of each, and no screen or keyboard.

2. The program. Software running on that machine that listens for requests. A "web server" is a program that answers web requests. A "database server" is a program that answers database queries. One machine can run many server programs at once.

3. The rented slice. When you "get a server" from a cloud provider, you almost never get a whole physical machine. You get a virtual server — a portion of a big machine, walled off so it behaves like its own computer. (Containers vs Virtual Machines explains how that slicing works.)

People slide between these meanings without noticing. Context usually tells you which one.

What happens when someone visits your app

They type yourapp.com. DNS turns the name into an IP address — the server's location. (DNS Records Explained.)
Their browser connects to that address and sends a request: "GET the home page."
The server program receives it, runs your app's code — maybe fetching data from a database — and builds a response.
It sends back HTML, images, or data. The browser displays it.

That round trip happens for every page, every image, every button that saves something. A busy app's server handles thousands of these a second.

Why not just use your laptop?

You can run your app on your laptop — that's what localhost is. (What Is localhost?.) But for real users, a laptop makes a poor server:

It sleeps, restarts, and leaves the house. A server must be on 24/7.
Your home connection isn't built for it. Your internet provider gives you a changing address, blocks incoming traffic by default, and has slow upload speeds.
It's a security risk. Opening your personal computer to the internet exposes everything on it.

Data centres solve all of this: constant power, fast networks, fixed addresses, and physical security.

Kinds of server you'll hear about

Physical / bare metal — a whole machine that's yours. Maximum power and control, most work.
Virtual private server (VPS) — a slice of a machine with full control of its operating system. You install and maintain everything. (VPS vs PaaS.)
Platform as a service (PaaS) — you hand over your code; the platform runs it on servers you never see or manage.
Serverless — there are still servers, but you don't manage or even think about them; your code runs on demand and you pay per use. (What Is Serverless?.)

For most people building their first app, the right answer is a platform that manages the server for you.

What a server needs to run your app

Whatever kind you choose, somewhere there's a computer that needs:

An operating system — almost always Linux.
Your app's runtime — Node.js, Python, and so on.
Your code and its dependencies.
Configuration — environment variables, secrets, the database address. (What Is an Environment Variable?.)
A way to reach it — a domain name and HTTPS.
Someone keeping it healthy — security updates, restarts after crashes, backups, monitoring.

That last item is the real cost of "having a server," and it's why managed hosting exists.

The summary

A server is a computer or program that answers requests.
"Getting a server" usually means renting a virtual slice of a big machine.
Your laptop can act as a server for testing, but not for real users.
Someone has to maintain it: you, or a platform that does it for you.

EasySpawn gives each project its own persistent Linux workspace on a managed server — with Docker isolation, daily backups, SSL, and your own domain — so you get a real server without having to be its system administrator. See how it works or join the waitlist.