Reusable Blocks are a great way to speed up your content creation workflow by allowing you to create your own custom block that's formatted in a way that you frequently use.
Let's create a new block and change the background colour. If we click on our block options and choose, "add to reusable blocks,"" we'll get the option to give our block a name - let's say 'blue'.
Now, if we ever want to do this again, instead of having to go in and change the background each time, we can just select the block we created from the reusable blocks.
But notice though, that we can't edit our block like normal. If you click the 'edit' button that appears, this will directly edit the template you created. So when you save, anything you change will change everywhere. If you want to change something in your block without changing others, you will need to go to the block options, and convert it to a regular block.
For more complex reusable blocks, such as ones that contain multiple types of blocks, you will first need to hold shift and select all of the blocks you want to include, before adding them to a reusable block. You can then use it, just as we did our first block.
If you ever wish to delete one of the blocks you created, you can always go to the reusable blocks sections, and click 'manage all reusable blocks'. From here you can edit, delete or export your blocks for use on another site.