Questions every good PHP Developer should be able to answer
<p>I was going through <a href="http://stackoverflow.com/questions/365489/questions-every-good-net-developer-should-be-able-to-answer">Questions every good .Net developer should be able to answer</a> and was highly impressed with the content and approach of this question and so in the same spirit, I am asking this question for PHP Developer.</p>

<p><strong>What questions</strong> do you think should a good <strong>PHP programmer be able to respond to?</strong></p>

<p><strong>EDIT</strong> : I am marking this question as community wiki as it is not user specific and it aims to serve programming community at large. </p>

<p>Looking forward for some amazing responses. </p>

<p><strong>NOTE</strong> : Please answer questions too as suggested in the comments so that people could learn something new too regarding the language. </p>
