title: How to identify an Application as Single threaded or Multi threaded?
body: <p>How can i know whether the Application i am developing is single threaded or multi threaded? 
  For example is StackOverflow a multi threaded or single thread Application?</p>
  
  <p>We all login into stackoverflow, does that mean... at the same time n users are trying to access stackoverflow login class... <code>checkLogin</code> Method? </p>
  
  <p>So should we declare the checkLogin method <code>synchronized</code>? </p>