Content permissions can be inherited from a Content Type, a "parent" folder, or individual content permissions (non-inherited), can be set on any content from the Content tab.
To view the permissions set on a content, right click on a piece of content displayed under the Content tab and click "Edit". Now click on the Permissions tab next to the content Properties tab.
Content Permission Inheritance from System Host
Below is an image of a content that is inheriting all its permissions from the "System Host". This means that permissions on this content, "parent" folder, and host above it, are inheriting permissions directly from the Role permissons themselves set at the System Host* level.
Setting Individual Permissions
While editing a content, clicking on the Permissions tab and the "Permission Individually" button will stop any role inheritance coming from higher up the permission hierarchy and allows for permissions to be set on the content itself.
*For more information on setting permissions on dotCMS objects from the System Host, please see the documentation on Role Permissions.