A portlet is information that is placed within a region on a page. All portlets come from a data source registered with Oracle Portal, called a portlet provider. Oracle Portal itself is a portlet provider, because certain aspects of the product have been made available so that you can include them on your own pages. This snapshot of the Oracle Portal home page, for example, shows three portlets, all from Oracle Portal:
By selecting the appropriate Oracle Portal portlet provider, you can place any of the portlets shown in this snapshot on your own pages. Oracle Portal also provides other portlet providers so that you can make most Oracle Portal objects available to your pages as well. For example, you can create a navigation bar for a folder on Company Activities--making sure you publish the navigation bar as a portlet--then place that navigation bar later on a page devoted to new hires at your company. You can also include data from a folder--or just items from a particular region within that folder--within a region on a page. Even other pages can be placed within a region on another page.
To see the complete list of objects you can place in a region, click 
while editing a page, then select an entry from the list of
Providers. Oracle Portal also provides instructions for creating your
own portlet providers, so that you can make data from your
proprietary applications available to your pages.