Android : Each Android thread is associated with Looper(Message Queue)?

I am trying to understand threads,handlers,loopers. I have watched the video where guy said following Each Android thread is associated with Looper(Message Queue). So that means that when I am creating Thread class instance it is implictly creates it own looper which is connected to this thread ? Or this is wrong ? Handler is connected to the thread where it was created, if there is no looper in each thread where handler will post messages ? And another question is about HandlerThread . What is the purpose and what are pros and cons of using this class. I hope for your help.Thanks everyone in advance.