The CERN Theme has 9 regions in total.
[Red in image below]
The header region is placed on the top of the website and includes elements like the logo, the site name and the main menu that you can set from the theme settings. It is highly recommended not to place more blocks in the header since it can support a specified amount of elements.
[Yellow in image below]
The left sidebar region holds 3 of the 12 bootstrap columns and can be used to place menus and views. In mobile version it is placed above the Main Content region.
[Blue in image below]
The main content region constitutes the region that holds the main information of a page. Moreover one can place extra views and blocks. It holds 6 of the 12 bootstrap columns and can be used to place the main content of the page. In the case where the left sidebar or right sidebar are absent (if no blocks are placed in those regions), then the main content holds 9 of the 12 bootstrap columns.
[Green in image below]
The right sidebar region holds 3 of the 12 bootstrap columns and can be used to mainly place menus and views. In mobile version it is placed after the Main Content region.
[Orange in image below]
The Content Footer region holds 12 of the 12 bootstrap columns and is placed under the Left Sidebar/ Main Content/ Right Sidebar regions. It can be used to mainly place views like the Horizontal Boxes carousel.
Footer: column 1/2/3/4
[Purple in image below]
The footer constitutes a branding element of the websites that use the CERN Theme. The common elements of the Footer are the CERN Logo, the Copyright text and the 4 regions of the footer. The footer can be used to place quick links in order to help the users navigate to external websites. It can also be used to place links of Social Media. The latter is easily achievable by using the CERN Full HTML text format along with the CERN font. The Footer column regions holds 3 of the 12 bootstrap columns each one of the columns (4 regions x 3 columns each = 12 bootstrap columns in total). It is mainly used to place either custom blocks to present information of the website, or menus to redirect users.