Regions and Layout OptionsRegions and Layout Options
Each CMS Drupal theme is designed with 17 regions. Regions are simply spaces in your theme that you can assign content blocks. 3 of the regions are designed as "Sidebars" as shown in the image below. You can assign blocks to the sidebar regions to create 1 to 4 column layouts. For example this page is a 2 column layout with the main content area on the left and a block with navigation links in the right sidebar. The sidebar regions are collapsible which means if you don't assign blocks to any of the sidebars then your main content area will expand the width of the page. The sidebar widths are also adjustable under the Layout settings link which is located on the theme settings page.
Note: The content top 2 and 3 regions are set at a width of 460 px each in all but the Credibility theme which has a featured slideshow that requires a 540 px width for the content top 2 region.