The Block module allows you to create boxes of content, which are rendered into an area, or region, of one or more pages of a website. The core Seven administration theme, for example, implements the regions "Content", "Help", "Dashboard main", and "Dashboard sidebar", and a block may appear in any one of these regions. The Blocks administration page provides a drag-and-drop interface for assigning a block to a region, and for controlling the order of blocks within regions. For more information, see the online handbook entry for Block module.


Positioning content
When working with blocks, remember that all themes do not implement the same regions, or display regions in the same way. Blocks are positioned on a per-theme basis. Users with the Administer blocks permission can disable blocks. Disabled blocks are listed on the Blocks administration page, but are not displayed in any region.
Controlling visibility
Blocks can be configured to be visible only on certain pages, only to users of certain roles, or only on pages displaying certain content types. Administrators can also allow specific blocks to be enabled or disabled by users when they edit their My account page. Some dynamic blocks, such as those generated by modules, will be displayed only on certain pages.
Creating custom blocks
Users with the Administer blocks permission can add custom blocks, which are then listed on the Blocks administration page. Once created, custom blocks behave just like default and module-generated blocks.