Reusable Content List is a SharePoint list comes up with any Publishing Site by default.
Using this list you can create plain text or HTML that can be reused throughout the site. Any content added to this list can also be set to automatically update pages.
For example such as , you can give copyright, Title in the Reusable Content List and you can use it anywhere in the page.
Steps:
1. Edit the page where you are going to use Reusable content.
2. Click on Insert Tab and select Reusable Content
3. Double Click on it and select the item.
Note:
I have attached the screenshots in a separate document.