Modules are more lightweight and flexible extensions used for page rendering. These modules are mostly known as the “boxes” that are arranged around a component, for example: the login module. The footer is a module. Modules are assigned per menu item. So, you can decide to show or hide the logon module depending on which menu item the user is viewing. Sometimes modules are linked to components such as the “latest news” module which links to the com_content and displays links to the newest content items. However, modules do not need to be linked to components, as a matter of fact they don’t even need to be linked to anything and can be just static HTML or text.
Examples: Banners (mod_banners), Menus (mod_menu), Who’s Online (mod_whosonline)
Management feature: Admin head menu > “Extensions” > “Module Manager”