# Domains and previews

Understand what a temporary preview exposes and what a stable domain promises to its users.

## From a port to a preview

An application listens on a port. A preview routes a browser request to that application so a person can inspect it. Check both the process and the application response before sharing a link.

## A domain is a stable entry

A custom domain gives people a recognizable address. Configure its DNS and platform binding, then verify the returned public route. Do not guess a deployment address from a name.

## Access is a separate decision

A reachable address does not imply that everyone should have permission to use it. Decide whether the route is public, authenticated or shared through a limited token.

## Connect the right resource

The [Connections lab](/docs/learn/labs/connections) helps distinguish a domain, a database binding and a persistent volume. Each connection has a different job.