When there is a need to set permission levels for the whole web application then there are the following four permission sets:
This is how we can create the user policy.
1. Open the SharePoint Central Administration
2. Click the “Manage Web Applications “under the “Application Management” heading.
3. Click the Web Application for which User Policy is to be created.
4. Now click on the User Policy.
Full Read - good for search/caching
Full Control - good for global admins
Deny Write - good for public facing
Deny All - good for restricted sites
Now click finish once done.