Question about the creation of Sitecore packages with the Package Designer
You use the Package Designer to create packages with Sitecore items that can be easily transferred, for example from one Sitecore website to another and opened in Sitecore. You can use Package Designer to create or modify packages that could contain dynamically or statically created items, or files. Packages that you create with the Package Designer can also contain security accounts.
Sitecore modules are packages. You can use the package to create modules. Some administrators use the packager to install updates to custom code and definition items.
Packages can contain serialized Sitecore items, files and security accounts. Sitecore package files have a .zip extension, but the format differs from the standard for zip archives. Packages are also used to install Sitecore modules which introduce additional features to the Sitecore user interface.