title: Equivalent of Alert() and Prompt() in PHP
body: <p>In JavaScript, we have Alert() and Prompt() which open up a popup box for the user.</p>
  
  <p>Is there an equivalent for PHP?
  <code>$Get_['asdf']</code> is one way to get user input... any others?</p>
  
  <p>Also, one more question. Is it a requirement that PHP always be executed all at once? Or can it be like JavaScript, where it waits for the user input (e.g. popup box), then executes the rest of the code after that.</p>