# PHP — The Web Scripting Language Powering Much of the Internet

> PHP is a popular general-purpose scripting language that is especially suited to web development. Fast, flexible, and pragmatic, PHP powers WordPress, Wikipedia, Facebook, Slack, and countless web applications worldwide.

## Install

Save in your project root:

## Quick Use

```bash
# Install
brew install php                           # macOS
sudo apt install php                       # Debian/Ubuntu
docker run --rm -it php:8.3 bash           # Docker

php --version
php -S localhost:8000                       # Built-in dev server
```

Hello world:
```php
<?php
// index.php
declare(strict_types=1);

function greet(string $name): string {
    return "Hello, " . $name;
}

$users = [
    ["name" => "Alice", "score" => 95],
    ["name" => "Bob",   "score" => 87],
];

usort($users, fn($a, $b) => $b["score"] <=> $a["score"]);

foreach ($users as $user) {
    printf("%s: %d\n", $user["name"], $user["score"]);
}
```

Composer (package manager):
```bash
curl -sS https://getcomposer.org/installer | php
sudo mv composer.phar /usr/local/bin/composer
composer init
composer require monolog/monolog
```

## Intro

PHP (originally Personal Home Page, later PHP: Hypertext Preprocessor) is a popular general-purpose scripting language especially suited to web development. Created by Rasmus Lerdorf in 1994. Despite endless declarations of its death, PHP 8.x powers a huge portion of the web: WordPress (40%+ of all websites), Wikipedia, Facebook (Hack/HHVM fork), Slack, Shopify, Mailchimp. Modern PHP is fast (JIT in 8.0+), typed (union types, readonly, enums), and has a mature framework ecosystem (Laravel, Symfony).

- **Repo**: https://github.com/php/php-src
- **Stars**: 39K+
- **Language**: C
- **License**: PHP License v3.01

## What PHP Does

- **Server-side scripting** — embedded in HTML or standalone
- **CLI execution** — scripts, CLIs, cron jobs
- **Built-in web server** — `php -S` for dev
- **Huge standard library** — strings, arrays, HTTP, crypto, DB, JSON
- **Frameworks** — Laravel, Symfony, CodeIgniter, Phalcon, Yii
- **CMS** — WordPress, Drupal, Joomla, Magento
- **ORM** — Eloquent (Laravel), Doctrine (Symfony)
- **Composer** — Packagist is the largest PHP package registry
- **JIT compiler** — OPcache + JIT in PHP 8.0+
- **Modern syntax** — union types, enums, readonly, attributes, first-class callable

## Architecture

Zend Engine interprets PHP bytecode. OPcache caches compiled bytecode between requests. PHP-FPM process manager serves requests behind Nginx or Apache. PHP 8 added a JIT tracing optimizer on top of OPcache for CPU-bound workloads.

## Self-Hosting

```bash
# Production stack
# PHP-FPM + Nginx
apt install php8.3-fpm nginx
systemctl enable php8.3-fpm nginx
```

## Key Features

- Embedded in HTML or standalone
- JIT compiler (8.0+)
- Union and intersection types
- Enums (8.1+)
- Readonly properties (8.1+) and readonly classes (8.2+)
- Attributes (metadata annotations)
- First-class callable syntax
- Composer package ecosystem
- Laravel and Symfony frameworks
- WordPress and many CMS

## Comparison

| Language | Use | Startup | Ecosystem |
|---|---|---|---|
| PHP | Web, CLI | Per-request | Huge (CMS) |
| Python | Web, ML, scripts | Per-request (uvicorn) | Huge |
| Ruby | Web, scripts | Per-request (Rails) | Large |
| Node.js | Web, CLI | Long-running | Huge |
| Go | Services | Long-running | Large |

## 常见问题 FAQ

**Q: PHP 过时了吗？**
A: 没有。现代 PHP (8.x) 类型系统、性能、工具都和其他主流语言接近。WordPress 之类的 CMS 还是 PHP 主导。Laravel 生态非常健康。

**Q: PHP vs Python web？**
A: PHP 在共享主机和 CMS 场景无可替代；Python 在 ML/数据 场景优势明显。Web 框架层面两者都很成熟（Laravel vs Django/FastAPI）。

**Q: JIT 有多快？**
A: CPU-bound 提升明显（2-3x），web IO-bound 提升不大（因为每次请求重新编译一遍 bytecode）。OPcache 才是 web 性能的关键。

## 来源与致谢 Sources

- Docs: https://www.php.net/docs.php
- GitHub: https://github.com/php/php-src
- License: PHP License

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Source: https://tokrepo.com/en/workflows/7cce7f80-3606-11f1-9bc6-00163e2b0d79
Author: AI Open Source