What is the case, the PHP code is mixed with the HTML code

This is what happens when the PHP code and the HTML code are mixed together
The code below, PHP functions and HTML code mixed together, how to explain?
I just self-taught PHP, some of the here do not understand, but also hope that you are not hesitate to enlighten.

Public Function Displaystyles ()
{
?>
  

 }

Public Function Displayheader ()
{
?>
  
 

 cellspacing= "0" border= "0" >
  
    
    
        
TLA Consulting Pty LTD

    
    
  
  

 }

------Solution--------------------
Yes, that's OK, for example.
$a = 3;
$b = 5;
if ($a > $b)
{
?>

Hello

}
Else
{
?>

World

}
?>

PHP language skills, sometimes it is very convenient to do so, you write more PHP, you will find the beauty of it
I'm not used to it at first, it's normal.
------Solution--------------------
You can put

function () {? >hello ' world
 
  

function () {echo ' hello\ ' World ';}

This is also for the sake of brevity, think, a string contains a lot of single double quotes, then how much trouble ah

------Solution--------------------
Your question is reasonable.

What does PHP do?
PHP is a widely used, open-source, multi-purpose scripting language that can be embedded in HTML, especially for Web development.

So embedding HTML code in the PHP code is really nondescript.
------Solution--------------------

 
  
  
   References:
  
   
  

   
    
   Reference: Yes, this is OK, for example
   
    
   

   
      $a = 3;
   
    
   
  $b = 5;
   
    
   
  if ($a > $b)
   
    
   
  {
   
    
   
?>
   
    
   

   
    
   
Hello
   
    
   

   
      }
   
    
   
  Else
   
    
   
  { 
   
    
   
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