PHP

PHP: Hypertext Preprocessor

File:Php-logo.svg PHP logo
Paradigm	Multi-paradigm: imperative, functional, object-oriented, procedural, reflective
Designed by	Rasmus Lerdorf
Developer	The PHP Group
First appeared	1995 (1995)
Stable release	8.4 / November 2024 (2024-11)
Typing discipline	Dynamic, weak, gradual
Implementation language	C
Platform	Cross-platform
OS	Cross-platform
License	PHP License (BSD-style)
Filename extensions	.php, .phtml, .php3, .php4, .php5, .php7, .phps
Website	www.php.net
Major implementations
Zend Engine, HHVM, Phalanger
Influenced by
C, Perl, Java, C++, Tcl
Influenced
Hack

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PHP (recursive acronym for PHP: Hypertext Preprocessor) is a general-purpose, server-side scripting language designed mainly for building dynamic web pages. It was created by Rasmus Lerdorf in 1994 and released publicly in 1995. PHP code is usually executed on a web server by the PHP interpreter, and its output — commonly HTML — is sent to the browser.

Also known as: PHP Hypertext Preprocessor, Personal Home Page Tools, Personal Home Page / Forms Interpreter (PHP/FI).

What is PHP?

PHP is a widely-used, open-source, general-purpose scripting language that is especially suited to web development and can be embedded directly into HTML. Rather than running in the browser like JavaScript, PHP runs on the server: the browser requests a page, the server runs the PHP script, and the finished HTML is returned. This makes PHP a server-side language.

PHP is platform-independent — it runs on Linux, Windows, macOS and most Unix-like systems — and is typically deployed alongside a web server such as Apache or Nginx and a database such as MySQL or MariaDB. That combination is often called a LAMP stack (Linux, Apache, MySQL, PHP).

What PHP means

PHP originally stood for Personal Home Page Tools, the name Rasmus Lerdorf gave his set of CGI scripts in 1994. The language was later renamed PHP/FI (Personal Home Page / Forms Interpreter) and then, with PHP 3 in 1998, given its current recursive meaning: PHP: Hypertext Preprocessor.

Who made it

PHP was created by Rasmus Lerdorf, a Danish-Canadian programmer, in 1994. The language is now maintained by The PHP Group and developed by a worldwide community of contributors, with the source code hosted publicly and released under the PHP License, a BSD-style licence.

When it started

• 1994 — Rasmus Lerdorf writes a set of CGI scripts to track visits to his online résumé; he calls them "Personal Home Page Tools".
• 1995 — PHP/FI 1.0 is released publicly; PHP/FI 2.0 follows with form handling and database support.
• 1998 — PHP 3.0 is released, rewritten from scratch by Andi Gutmans and Zeev Suraski, and the recursive name "PHP: Hypertext Preprocessor" is adopted.
• 2000 — PHP 4.0 introduces the Zend Engine, sessions and better object support.
• 2004 — PHP 5.0 adds a much stronger object model.
• 2015 — PHP 7.0 brings large performance gains and modern type hints.
• 2020 — PHP 8.0 introduces a JIT compiler, union types, named arguments and the match expression.
• 2024 — PHP 8.4 is released.

What PHP is used for

• Web pages — generating HTML, handling forms and managing sessions.
• Web applications — content management systems, forums, shops and dashboards.
• APIs — returning JSON or XML from REST endpoints.
• Command-line scripts — cron jobs, batch processing and small utilities.
• Templates — server-side templating inside HTML files.

PHP is the server-side language behind a large share of the web's sites, including WordPress, Drupal, Joomla, MediaWiki, Magento, Laravel applications and Wikipedia itself.

How it works

1. Write the script — a file ending in .php containing PHP blocks, usually opened with <?php and closed with ?>, mixed with HTML.
2. Send a request — a browser (or API client) asks the web server for the page or endpoint.
3. The server runs PHP — the web server hands the file to the PHP interpreter, which executes the code.
4. The output goes back — whatever the script prints, typically HTML, is sent to the browser as the response.

A minimal example:

<?php
echo "Hello, world!";
?>

Features

• Embeddable — PHP can sit directly inside HTML.
• Open source — free to use, modify and redistribute under the PHP License.
• Cross-platform — runs on most operating systems and web servers.
• Broad database support — built-in extensions for MySQL, PostgreSQL, SQLite, Oracle and more.
• Huge standard library — hundreds of built-in functions for strings, files, dates, arrays, HTTP and beyond.
• Large ecosystem — Composer for package management, plus frameworks such as Laravel, Symfony and CodeIgniter.
• Wide hosting support — the overwhelming majority of shared web hosts run PHP out of the box.

Advantages and disadvantages

Advantages:

• Very low barrier to entry, and near-universal on cheap hosting.
• Massive ecosystem, documentation and community.
• Fast enough for most web workloads, and much faster since PHP 7.
• Native templating makes it easy to mix markup and logic.

Disadvantages:

• Historically inconsistent function naming and argument order in the standard library.
• Weaker type safety than statically typed languages, though modern versions have improved this considerably.
• A large body of older code predates current security and style practices.

History

• 1994 — Rasmus Lerdorf writes the first PHP scripts.
• 1995 — PHP/FI 1.0 released publicly.
• 1997 — PHP/FI 2.0 released.
• 1998 — PHP 3.0 released; renamed PHP: Hypertext Preprocessor.
• 2000 — PHP 4.0 released with the Zend Engine.
• 2004 — PHP 5.0 released with a new object model.
• 2015 — PHP 7.0 released with major performance improvements.
• 2020 — PHP 8.0 released with JIT and new syntax features.
• 2024 — PHP 8.4 released.

See also

• Rasmus Lerdorf
• Zend Engine
• Composer (software)
• Laravel
• MediaWiki
• LAMP (software bundle)