If else embedding inside html

What is the correct way of embedding if else and elseif conditions inside html?

I recommend the following syntax for readability.

<? if ($condition): ?>
  <p>Content</p>
<? elseif ($other_condition): ?>
  <p>Other Content</p>
<? else: ?>
  <p>Default Content</p>
<? endif; ?>

Note, omitting php on the open tags does require that short_open_tags is enabled in your configuration, which is the default. The relevant curly-brace-free conditional syntax is always enabled and can be used regardless of this directive.

<?php if ($foo) { ?>
    <div class="mydiv">Condition is true</div>
<?php } else { ?>
    <div class="myotherdiv">Condition is false</div>
<?php } ?>

In @Patrick McMahon's response, the second comment here ( $first_condition is false and $second_condition is true ) is not entirely accurate:

<?php if($first_condition): ?>
  /*$first_condition is true*/
  <div class="first-condition-true">First Condition is true</div>
<?php elseif($second_condition): ?>
  /*$first_condition is false and $second_condition is true*/
  <div class="second-condition-true">Second Condition is true</div>
<?php else: ?>
  /*$first_condition and $second_condition are false*/
  <div class="first-and-second-condition-false">Conditions are false</div>
<?php endif; ?>

Elseif fires whether $first_condition is true or false, as do additional elseif statements, if there are multiple.

I am no PHP expert, so I don't know whether that's the correct way to say IF this OR that ELSE that or if there is another/better way to code it in PHP, but this would be an important distinction to those looking for OR conditions versus ELSE conditions.

Source is w3schools.com and my own experience.