What are Regions and Blocks in Drupal theme?

- Drupal uses 'regions' as 'areas in the layout'.  By default there is a header, footer, content region, left and right sidebar.
- You can add your own regions to a theme.
- Drupal uses blocks as 'boxes' to put into regions of a site.
- The area where designers generally put 'editable regions' for content is in the 'content region'.