The Divi Library is where you can save presets for later use. When you create your site, different useful sections will automatically be added to the library. These are the same sections that are used to create the home page when you first set up your site.
Using elements from the Divi Library
When you go to insert a new section, row, or module, switch to the Add From Library tab. You will then see the list of items saved to your Divi Library.
You can also replace the entire content of your page to a layout saved to the Divi Library, or to any number of premade layouts created by the Elegant Themes team. To do this, click on the Load from Library button in the Global Settings menu.
Saving elements to the Divi Library
Hover over the item you want to save and click the “Save to Library” button. Give the item a name and click save.
If you want you can tick “Make this a global item”. See Elegant Theme’s documentation for more information on what this means.