title: What are Perl built-in operators/functions?
body: <p>I'm reading <em><a href="http://learn.perl.org/books/beginning-perl/" rel="nofollow">Beginning Perl</a></em> by Simon Cozens and in <em>Chapter 8 - Subroutines</em> he states that "subroutines" are user functions, while <code>print</code>, <code>open</code>, <code>split</code>, etc. are built-in operators or functions.</p>
  
  <p>What are they? Are they really built-in, language-intrinsic features (like C's <code>sizeof</code> operator) or are they, actually, subroutines/functions of the <code>main</code> module?</p>
  
  <p>If they're subroutines, are <code>while</code>, <code>for</code>, <code>unless</code>, etc. also subroutines? What about the operators like <code>+</code>, <code>-</code>, <code>eq</code>, etc.?</p>