Quick definition · 2 min Coding term
Dev server
A dev server is a program on your computer that shows a live, instantly-updating preview of your app while you build it.
Think of it like
A mirror that updates as you get dressed. Change something and the preview changes right away.
Example
“Run the dev server” or npm run dev starts it; then you open the localhost link and watch your app update as you edit.
Why it matters
It is the single most repeated instruction in AI coding tools, yet rarely explained. It is just your live practice preview.
Where you’ll see it
CursorVS Codeyour terminal