"Modules" are modular pieces of code that each present some functionality to the user.  Popular modules include user forums, photo galleries, blog publishers, directory tools, chat applications, contact managers, and events calendars. 

In typical use cases, several modules will be grouped together to create a webpage or intranet page.  These modules can easily be added, edited, deleted, restored, moved within a tab, or transfer to another page.

Within the DotNetNuke ecosystem, hundreds of developers continually produce new modules for the DotNetNuke application framework. These module developers often build modules which they sell on their sites or through marketplaces such as Snowcovered.com. Some developers offer modules for free and thousands of modules are available for DotNetNuke. Developers often offer their services to design custom modules for their clients.