When workflow is defined for a content item, promoting the content first routes it through the workflow. In this case, the content must be approved by the appropriate reviewer(s) before being promoted to the Staging Sandbox.
You can validate the website links in both your user sandbox before submitting the content and in the Staging Sandbox after the snapshot has been created. You can also check the links as part of the submit process. If broken links are found, the content set is not promoted to staging. Instead, a task is added to your My Tasks To Do list in the dashboard prompting you to verify and correct the broken links.
As part of submission, you have the option to set a launch date and time for the content set. Upon approval, the content set will be promoted to a separate staging area: the Content Awaiting Launch list in the Staging Sandbox. The content is held here until the launch date. See Content Launch and Expiration for further information.
The end result of the Submit action is a snapshot in the Staging Sandbox: an archive of the current version of the site.