title: endl and flushing the buffer
body: <p>In the <strong>C++ primer</strong> book, in chapter (1), it mentions the following:</p>
  
  <blockquote>
    <p>endl is a special value, called a manipulator, that when written to an
    output stream has the effect of writing a newline to the output and
    <strong>ﬂushing the buffer associated with that device</strong>. <strong>By ﬂushing the buffer, we ensure that the user will see the output written to the
    stream immediately.</strong></p>
  </blockquote>
  
  <p>What is meant by "flushing the buffer" here?</p>