...More specifically, it provides a Scheduler that schedules on the main thread or any given Looper. Additional binaries and dependency information for can be found at search.maven.org. One of the most common operations when dealing with asynchronous tasks on Android is to observe the task's result or outcome on the main thread. Using vanilla Android, this would typically be accomplished with an AsyncTask. With RxJava instead you would declare your Observable to be observed on the main thread.