Ever have a situation where you want to put a module in an article? Maybe a login form or a menu? Well, in Joomla 3 there is a core plug-in that provides for this.
To use it, create your module. Do not choose a position. Make sure the module is published. Page assignment is irrelevant since the position isn't on any page, it won't show up even if you set it to all pages.
Save the module, and navigate to the article that you want it to show up in. Place your cursor where you want the module placed and below the content box is a Module button. Click that and navigate to the module you just created. Save and go to the page on the front end and refresh the page. You should see your module in the article. That is all there is to it!
Want to do the opposite? Put an article in a module?
That is not part of the core of Joomla, but there is a free extension that makes it easy.