A PHP script starts with the <?php and ends with the ?> tag which tell PHP to start and stop interpreting the code between them and Every PHP statement end with a semicolon (;)
Below the example of long tag:
<?php echo 'Hello, World'; ?>
PHP also allows for short open tag <? (which is discouraged since it is only available if enabled using the short_open_tag php.ini configuration file directive, or if PHP was configured with the --enable-short-tags option).
<?= are called short open tags, and are not always enabled
short_open_tag directive) with PHP 5.3 or below (but since PHP 5.4.0,
<?= is always available).
Below the example of short tag:
<?= 'Hello, World'; ?>