title: What does the dollar sign mean in PHP?
body: <p>What does the dollar sign mean in PHP?  I have this code:</p>
  
  <pre><code>&lt;?php
    class Building {
      public $number_of_floors = 5;
      private $color;
  
      public function __construct($paint) {
        $this-&gt;color = $paint;
      }
  
      public function describe() {
        printf('This building has %d floors. It is %s in color.', 
          $this-&gt;number_of_floors, 
          $this-&gt;color
        );
      }
    }
  
    $bldgA = new Building('red');
  
    $bldgA-&gt;describe();
  ?&gt;
  </code></pre>
  
  <p>It seems that the <code>$</code> indicates a variable like:</p>
  
  <pre><code>$number_of_floors
  $color
  </code></pre>
  
  <p>But I get confused when I see the following:</p>
  
  <pre><code>$bldgA-&gt;describe();
  $bldgA-&gt;number_of_floors;
  </code></pre>
  
  <p>Why are there no dollar signs before these variables?</p>