Security within SharePoint 2013
It can be easy to lose track of who has access to your sites and libraries. You can use the tools on the SharePoint 2013 ribbon to check what permissions are on an entire site or to view a summary of the permissions assigned to a group or individual.
View permissions on a library or list
On the Quick Launch bar, click Site Contents.
Click the drop-down ellipsis to the right of the library with which you want to work. (Hover over the library for the drop-down indicator to display).
On the menu that appears, click Settings.
On the Library Settings page, in the Permissions And Management group, click Permissions For This Document Library.
On the Permissions tab, review each group name and permission level.
Check permissions for an individual or group
On the Home page, click the Settings button (the small gear icon next to the name of the logged-on user). On the menu that appears, click Site Settings.
On the Site Settings page, in the Users And Permissions section, click Site Permissions.
On the Permissions tab, in the Check group, click Check Permissions.
In the Check Permissions dialog box, in the User/Group text box, enter the name of the person or group.
Click Check Now.
In the Check Permissions dialog box, review the permission level summary.