# Service Usage

A service contains business logic that can be re-used across a Grails application. In Grails a service is a class that ends in the convention "Service" and lives in the `grails-app/services` directory. A service can be created with the create-service command:

    grails create-service Book

Or via your favourite IDE or text editor.

    class BookService {
    	Book[] getBooks() {
    		Book.list() as Book[]
    	}
    }

Refer to the user guide topic on Services for more information.