Short Tags

PHP uses special tags to identify code that has to be executed. The short tags are a special set of PHP tag, shorter than the usual <?php. It was simply <?.

Short tags may be disabled in PHP configuration, with the short_open_tag directive.

Short tags are different from echo tags: those tags immediately display data.

From the manual: As short tags can be disabled it is recommended to only use the normal tags <?php ?> and <?= ?> to maximise compatibility.

<?php

echo 1;
?>

<?
// this is a short tag
echo 2;

?>

Documentation

See also PHP RFC: Deprecate short open tags, again.

Related : PHP Tags, Echo Tag, Open Tag, Close Tag, Operators