Localhost
ELI5 — The Vibe Check
Localhost is your computer pretending to be a web server just for you. When you type localhost:3000, you're visiting a website that only exists on your machine — the whole internet can't see it. It's your private development playground.
Real Talk
Localhost refers to the loopback network interface (IP 127.0.0.1) that routes traffic back to the same machine. Developers run servers on localhost to test without deploying. Conventionally combined with a port number (e.g., localhost:8080).
When You'll Hear This
"The app is running on localhost:3000." / "It works on localhost but breaks in production — environment difference."
Related Terms
Config
Config is the settings panel for your code.
Deploy
Deploying is taking your code from your computer and making it live on the internet for real users. Before: only you can see it.
Hot Reload
Hot reload updates your running app when you change code without restarting the whole server. Edit a file, save, and see the change instantly.
Port
A port is like an apartment number on a building. Your computer is the building (localhost), and multiple services live inside.
Sandbox
A sandbox is a safe, isolated play area where code can run without affecting anything real.