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<h1>General Information</h1>
<p class="para">
This section holds the most general questions about PHP:
what it is and what it does.
</p>
<div class="qandaset"><ol class="qandaset_questions"><li><a href="#faq.general.what">
What is PHP?
</a></li><li><a href="#faq.general.acronym">
What does PHP stand for?
</a></li><li><a href="#faq.general.relation-versions">
What is the relation between the versions?
</a></li><li><a href="#faq.general.running-concurent">
Can I run several versions of PHP at the same time?
</a></li><li><a href="#faq.general.differences-45">
What are the differences between PHP 4 and PHP 5?
</a></li><li><a href="#faq.general.bug">
I think I found a bug! Who should I tell?
</a></li></ol></div>
<dl class="qandaentry" id="faq.general.what">
<dt><strong>
What is PHP?
</strong></dt>
<dd class="answer">
<p class="para">
From the <a href="preface.html" class="link">preface of the manual</a>:
</p>
<p class="para">
PHP is an HTML-embedded scripting language. Much of
its syntax is borrowed from C, Java and Perl with a couple of unique
PHP-specific features thrown in. The goal of the language is to
allow web developers to write dynamically generated pages quickly.
</p>
</dd>
</dl>
<dl class="qandaentry" id="faq.general.acronym">
<dt><strong>
What does PHP stand for?
</strong></dt>
<dd class="answer">
<p class="para">
PHP stands for <em class="emphasis">PHP: Hypertext Preprocessor</em>.
This confuses many people because the first word of the acronym is
the acronym. This type of acronym is called a recursive acronym.
For more information, the curious can visit
<a href="http://foldoc.org/" class="link external">» Free On-Line Dictionary of Computing</a>
or the
<a href="http://en.wikipedia.org/wiki/Recursive_acronym" class="link external">» Wikipedia entry on
recursive acronyms</a>.
</p>
</dd>
</dl>
<dl class="qandaentry" id="faq.general.relation-versions">
<dt><strong>
What is the relation between the versions?
</strong></dt>
<dd class="answer">
<p class="para">
PHP/FI 2.0 is an early and no longer supported version of PHP. PHP 3
is the successor to PHP/FI 2.0 and is a lot nicer. PHP 5 is the current
generation of PHP, which uses the <a href="http://www.zend.com/" class="link external">» Zend
engine 2</a> which, among other things, offers many additional
<a href="language.oop5.html" class="link">OOP</a> features.
</p>
</dd>
</dl>
<dl class="qandaentry" id="faq.general.running-concurent">
<dt><strong>
Can I run several versions of PHP at the same time?
</strong></dt>
<dd class="answer">
<p class="para">
Yes. See the <var class="filename">INSTALL</var> file that is included
in the PHP source distribution.
</p>
</dd>
</dl>
<dl class="qandaentry" id="faq.general.differences-45">
<dt><strong>
What are the differences between PHP 4 and PHP 5?
</strong></dt>
<dd class="answer">
<p class="para">
While PHP 5 was purposely designed to be as compatible as
possible with previous versions, there are some significant
changes. Some of these changes include:
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">A <a href="language.oop5.html" class="link">new OOP model</a>
based on the <em class="emphasis">Zend Engine 2.0</em></span>
</li>
<li class="listitem">
<span class="simpara">A new extension for improved MySQL support</span>
</li>
<li class="listitem">
<span class="simpara">Built-in native support for SQLite</span>
</li>
<li class="listitem">
<span class="simpara">A new error reporting constant,
<a href="migrating5.errorrep.html" class="link">E_STRICT</a>,
for run-time code suggestions
</span>
</li>
<li class="listitem">
<span class="simpara">A host of new
<a href="migration5.functions.html" class="link">functions</a>
to simplify code authoring (and reduce the need to write your own
functions for many common procedures)
</span>
</li>
</ul>
For more detailed information, please view the section on
<a href="faq.migration5.html" class="link">Migrating from PHP 4 to
PHP 5</a> and the section on
<a href="migration5.incompatible.html" class="link">Backwards
Incompatible Changes</a>.
</p>
</dd>
</dl>
<dl class="qandaentry" id="faq.general.bug">
<dt><strong>
I think I found a bug! Who should I tell?
</strong></dt>
<dd class="answer">
<p class="para">
You should go to the PHP Bug Database and make sure the bug
isn't a known bug. If you don't see it in the database, use
the reporting form to report the bug. It is important to use
the bug database instead of just sending an email to one of the
mailing lists because the bug will have a tracking number assigned
and it will then be possible for you to go back later and check
on the status of the bug. The bug database can be found at
<a href="http://bugs.php.net/" class="link external">» http://bugs.php.net/</a>.
</p>
</dd>
</dl>
</div>
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