title: php: about parsing and interpreting process
body: <p>I always see  <code>parse</code> or <code>compile</code> in tech articles. So I want to know how PHP works . I found out PHP is Interpreted language, not compiled. I googled online about <code>parse</code>, <code>Interpret</code> and <code>compile</code>, but still not that clear on the whole process. Below is an example PHP code:</p>
  
  <pre><code>&lt;?php
  $str1="Hello world!";
  $str2="What a nice day!";
  echo $str1 . " " . $str2;
  ?&gt;  
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>Hello world! What a nice day! 
  </code></pre>
  
  <p>Can anyone explain the whole process(parse, interpret...) from source code to the output? thanks</p>