title: How to prepopulate input text fields with prompting text which disappears on typing (jQuery)
body: <p>When you click on the <code>"Ask Question"</code> button on Stack Overflow, the question title section is prepopulated with light gray text that reads </p>
  
  <pre><code>"what's your programming question? be specific"
  </code></pre>
  
  <p>Then when you click inside the Title field and start typing, that text disappears.</p>
  
  <p>I want to do the same thing in my app.</p>
  
  <p>Is there a trick in jQuery to accomplish that? </p>
  
  <p><strong>And, specifically, how do you change the text color from light gray for the placeholder text to the default text color when someone starts typing?</strong></p>