We can group dependencies in a module for example Network module can provide HTTPClient Retrofit,GSON, HTTP Logger etc.
similarly we can have Database Module, Application Module, or any feature specific module.
Component is a bridge between Module(provider) and Activity/Fragment(Consumer) and it can have more than one module.
Inside Activity/Fragment we can get these dependencies by defining like below
@Inject
Gson gson;
these dependency will be fulfilled as soon as you inject the component(in this case network component which contains network module which contains Gson Provider method)
getNetworkComponent().inject(MyActivity.this/MyFragment.this)
here is a very good tutorial with simple example
https://code.tutsplus.com/tutorials/dependency-injection-with-dagger-2-on-android–cms-23345
In other words
A dependency consumer asks for the dependency(Object) from a dependency provider through a connector.
Dependency provider:
Classes annotated with @Module are responsible for providing objects which can be injected. Such classes define methods annotated with @Provides. The returned objects from these methods are available for dependency injection.
Dependency consumer:
The @Inject annotation is used to define a dependency.
Connecting consumer and producer:
A @Component annotated interface defines the connection between the provider of objects (modules) and the objects which express a dependency. The class for this connection is generated by the Dagger.