Blocks are the boxes of content (such as "User Login" or "Main Menu") that are displayed in Layout Regions (such as footer or sidebar) on your page. Everything on a Backdrop web page (with rare exceptions) is a block and can be placed in any region in a layout.
There are two main types of blocks:
- Standard blocks - are made available to your site most commonly by enabling modules.
- Custom blocks - are created by the site user and are essentially text (and image) blocks.
Blocks are placed in regions via the Layout UI page at Admin > Structure > Layouts . Your layout's template defines the regions available. Any block can be placed in any region and can be placed multiple times.