1. Introduction to PHP & The Web Development Stack
What is PHP?
PHP (Hypertext Preprocessor) is a popular general-purpose scripting language that is especially suited to web development. It is fast, flexible, and pragmatic.
- Server-Side: PHP code is executed on the server, generating HTML which is then sent to the client (browser).
- Open Source: It is free to use and distribute.
- Popularity: It powers millions of websites, including major platforms like WordPress, Facebook, and Wikipedia.
The LAMP Stack
To build dynamic websites, PHP usually operates within a technology stack. The most common is LAMP (or WAMP/MAMP):
| Acronym | Technology | Role |
|---|---|---|
| L/W/M | Linux, Windows, or macOS | Operating System |
| A | Apache | Web Server (Handles HTTP requests) |
| M | MySQL/MariaDB | Database (Stores data) |
| P | PHP | Processing Language (Handles business logic) |
How PHP Works
- A user's browser requests a
.phpfile from the server. - The web server (e.g., Apache) sees the
.phpextension and passes the file to the PHP interpreter. - The PHP interpreter executes the PHP code, interacts with the database (if needed), and generates plain HTML.
- The server sends the resulting HTML back to the browser.
- The browser renders the HTML.
mermaid sequenceDiagram actor Browser participant Server participant PHP Browser->>Server: Request index.php Server->>PHP: Execute PHP code PHP-->>Server: Return generated HTML Server->>Browser: Send HTML response