There are two types of custom settings in Salesforce: List Custom Settings and Hierarchy Custom Settings.
List Custom Settings are a type of custom settings that provides a reusable set of static data that can be accessed across your organization irrespective of user/ profile.
Hierarchy Custom Settings are another type of custom settings that uses built-in hierarchical logic for “personalizing” settings for specific profiles or users.
The advantage of using custom settings is that it allows developers to create a custom set of access rules for various users and profiles.