title: Difference between process and thread
body: <p>I was asked a question during interview today. First they asked how to provide Synchronization
  between thread. Then they asked how to provide Synchronization between process, because I told them, the variable inside each process can not be shared with other process, so they asked me to explain how two process can communicate with each other and how to provide Synchronization 
  between them, and where to declare the shared variable? Now the interview finished, but I want to know the answer, can anyone explain me?Thank you.</p>