Managing the Master Page Lifecycle
When saving master pages in SharePoint Designer where the site or site collection has the publishing Feature enabled, there are some additional steps you go through as part of the versioning and publishing workflow approval process. If you are saving master pages to non-publishing sites, or to a SharePoint Foundation 2010 site, then there is no additional effort involved; you simply save the master page to the Master Page Gallery and then set the master page as the default (or system) master page for the site. If you fail to check in and publish a master page in a publishing site then regular users cannot see the new master page or, worse, the site fails when they attempt to access it.
It is important ...