A development server serves an application during active implementation and may provide automatic reloads, source maps, diagnostic output, and other conveniences. It commonly runs as a continuing terminal process beside the editor or coding agent that changes the project.
Development servers are not automatically safe or suitable for public production traffic. They may expose debug information, use relaxed settings, or lack production performance and security controls, so their network access should remain appropriately scoped.
ELI5
A development server runs a work-in-progress application so developers can quickly see and test their changes. It is designed for building and debugging rather than for serving the final product to large numbers of users.
For example, a coding agent can start a local website server in one terminal pane while editing code in another. The browser then refreshes with the new version, and server errors remain visible beside the main task.
