Why do we need a level of service?

Question

I am currently studying Spring Boot, and I have seen people create a controller, implement a service class and implement a repository in a service class.

Why do we need a service class as an intermediary and why can't we just enter the repository into the controller?

Here's a lesson that confused me: https://www.youtube.com/watch?v=lpcOSXWPXTk&list=PLqq-6Pq4lTTbx8p2oCgcAQGQyqN8XeA1x

Answer 1

You do not always need a level of service. Especially if your APIs are just simple CRUD operations, for example, without real logic or computation.

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