What is the service layer pattern for?

Question

Design patterns

Hello, please tell me what is such a design pattern as a service layer (service layer)? What is it for?

Answer 1

It is needed in order not to violate the DRY SOLID principle (do not copy-paste the code) and to separate some application logic into a separate service class.
Saves a little from shitty code in small applications, but not much (read about DDD).