title: What's git bash and why it is mingw64 after opening it?
body: <p>I have done researching but still confused. 
  Is <code>git bash</code> windows' git console or something? 
  I opened it and it is <code>mingw64</code> on the title bar. 
  Is <code>mingw64</code> similar to <code>cygwin</code> or <code>putty</code> or what? 
  Please explain. Thanks.</p>