When PHP parses a file, it looks for opening and closing tags, which are
<?php and ?> which tell PHP to
start and stop interpreting the code between them. Parsing in this manner
allows PHP to be embedded in all sorts of different documents, as
everything outside of a pair of opening and closing tags is ignored by the
PHP also allows for short open tag <? (which is
discouraged since it is only available if enabled using the
configuration file directive, or if PHP was configured with the
If a file is pure PHP code, it is preferable to omit the PHP closing tag
at the end of the file. This prevents accidental whitespace or new lines
being added after the PHP closing tag, which may cause unwanted effects
because PHP will start output buffering when there is no intention from
the programmer to send any output at that point in the script.
<?php echo "Hello world";
// ... more code
echo "Last statement";
// the script ends here with no PHP closing tag
The ASP tags <%, %>,
<%=, and the script tag
<script language="php"> are removed from PHP.
The tag <?= is always available regardless of the short_open_tag ini setting.