Custom Setting

Hello Vijay,

All custom settings data is exposed in the application cache, which enables efficient access without the cost of repeated queries to the database. This data can then be used by formula fields, validation rules, flows, Apex, and the SOAP API.

you can refer to the below given link :

https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_customsettings.htm