Authorities are a helpful way of providing data catalogers with a list of controlled vocabularies. This helps ensure data consistency across a collection. Authorities are created in the Collection Manager by designating a field group as an Authority.
If you have permission to makes changes to an authority you'll see the "Manage Authorities" button next to the "New Record" button in the Library. When you mouse over the button you'll see the list of available authorities. In the example below there are 6 different authorities within this collection.
When you select an authority you'll be taken the a list view wherein all available data values for that specific authority are listed. Let's pick "SubjectHeadingsGroup" as an example. When this authority was created in the templates section of the Collection manager there were 2 fields added to the SubjectHeadingsGroup field group, "Subject" and "General Subject":
These two fields are now represented in the authority:
To edit a value in the authority select it and click on the "edit" icon. Or, you can select several and click on the "Edit" option from the Edit menu. Click on the trash icon to delete it.
Once you are in the edit mode simply make the desired edits and save. You can also use the "Show records using this authority" button to help give you an idea of which records will be affected by any changes to the value. Any edit made to an value will be reflected in ALL the records that use that authority value.
With the right permissions you can create new authorities, and upload a .csv list of authorities. Catalogers would then easily pick from the list of available data. Authorities are managed in the Library, and permission for managing them in the Administrator.