There are two types of deployment on the Vercel platform: preview and production.

Preview

Preview deployments are the default for all deployments. Each time you push to a branch or make a deployment using the vercel command, this is a preview deployment.

By making a preview deployment, the preview URL will be updated to reflect that of the latest deployment made.

The preview URL is provided on a pull or merge request when using Git and contains the name of the user or team to which the Project belongs.

If you request a preview URL, the X-Robots-Tag HTTP header will be set as noindex. This ensures that preview URLs will not be indexed by search engines such as Google. The only exception to this behavior exists when a custom domain is assigned to a preview branch. A custom domain assigned to a preview deployment will not set the the X-Robots-Tag header with the value noindex. Learn more about X-Robots-Tag by visiting Google Search Reference.

Production

Production deployments are made in two different circumstances. Each time you merge to the Production Branch (commonly main) or make a deployment using the vercel --prod command, this is a production deployment.

By making a production deployment, the production domain(s) will be updated to reflect that of the latest deployment.

The production domain(s) are defined from the Domains tab of a Project on the Vercel Dashboard.

To add a production domain to a Project, visit Domains from the Project Overview page, you can read more about this in the custom domains documentation.