Uniquely secured content is any content that does not inherit permissions from a parent. For example, if a site breaks inheritance with its parent site, that site is uniquely secured content and has its own unique permissions settings.
When you work with permissions on your site, you might notice that SharePoint displays a message about permissions on the Site Permissions page. If the site has uniquely secured content, the message states,”Some content on this site has different permissions from what you see here,” as shown in the following screen shot.
By default, lists, libraries, and other items inherit permissions from the site that contains them. The site inherits permissions from the site collection root site.
Under certain circumstances, content might have unique permissions. There are two different scenarios for this.
Access to the content is restricted. For example, if the content owner is still developing the content, the owner might not want anyone else to view or modify it.
Access to the content is expanded. In this scenario, a site user might decide to share a document with someone who does not have access. The site user can simply click Share on the ribbon, and provide the email address or username of the person who gets access.
You can set unique permissions for the following types of content:
To learn more about how to uniquely secure content, see Edit permissions for a list, library, or individual item.