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

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

Within the DotNetNuke ecosystem, hundreds of developers continually produce new modules for the DotNetNuke platform. 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.