Lesson 1: What is PHP

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1.1 History of PHP

  • Origin:
    • PHP (Hypertext Preprocessor) was created in 1994 by Rasmus Lerdorf.
    • Initially designed as a set of Common Gateway Interface (CGI) binaries to track visitors to his website.
  • Evolution:
    • 1995: PHP/FI (Personal Home Page/Forms Interpreter) released.
    • 1997: PHP 2.0 introduced by Zeev Suraski and Andi Gutmans.
    • 1998: PHP 3.0 – Redesigned engine, increased popularity.
    • 2000: PHP 4.0 introduced the Zend Engine.
    • 2004: PHP 5.0 introduced advanced OOP features.
    • Current Version: PHP 8.x with major performance improvements and new features like Just-In-Time (JIT) compilation.

1.2 Features of PHP

  • Open Source: Free to use and modify.
  • Cross-Platform: Runs on Windows, Linux, macOS, etc.
  • Server-Side Scripting: Executes on the server, outputs HTML to the client.
  • Database Integration: Supports MySQL, PostgreSQL, SQLite, and more.
  • Scalability: Suitable for small websites to large-scale web applications.
  • Community Support: Extensive online resources and libraries.
  • Dynamic Content: Enables dynamic and interactive web pages.
  • Security Features: Tools to prevent SQL injection, XSS, and more.

1.3 How PHP Works with Web Servers

  • PHP and Apache/Nginx:
    • PHP works as a module or via FastCGI with web servers like Apache and Nginx.
    • The web server sends HTTP requests to the PHP processor.
  • Execution Flow:
    1. A user requests a PHP page via a browser (e.g., index.php).
    2. The web server passes the request to the PHP interpreter.
    3. The PHP interpreter processes the PHP code and generates HTML.
    4. The web server sends the HTML back to the user’s browser.