Questions relating to the Express Migrations Tool, used to simplify the process of upgrading older versions of Sitecore to the latest releases.
When you need to update Sitecore v7.2/6.6 (or any supported version of the migration tool) to the latest release, the Express Migration Tool helps to speed up the upgrade process by migrating the data to a latest version instance. This reduces the complexity of bringing an older site up to the latest version.
It is documented here: https://dev.sitecore.net/Downloads/Express_Migration_Tool.aspx
