What functions do annotations in the Retrofit library perform when implementing network requests?

In Retrofit, annotations are used to describe HTTP requests and their parameters directly in the API interface. They define:

• Request type: @GET, @POST, @PUT, @DELETE, etc.
• Request path: specified in the annotation parameter, for example @GET("users/{id}").
• Request parameters: @Path, @Query, @Body, and others for data transmission.
• Headers: @Header for adding HTTP headers.

Example:

public interface ApiService {
    @GET("users/{id}")
    Call<User> getUser(@Path("id") int userId);
}

Annotations allow declarative description of network calls, simplifying their implementation and maintenance.