PHP (Hypertext Preprocessor) is a server-side scripting language widely used for web development. It works by enabling the execution of code on the server before the web page is sent to the user's browser. Here's a simplified overview of how PHP works in a web context:
1. **Embedding PHP in HTML:**
- PHP code is typically embedded within HTML files. PHP code is enclosed within `<?php` and `?>` tags. These tags indicate where PHP code begins and ends.
```php
<!DOCTYPE html>
<html>
<head>
<title>PHP Example</title>
</head>
<body>
<?php
// PHP code goes here
echo "Hello, World!";
?>
</body>
</html>
```
2. **Client Request:**
- When a user requests a web page that contains PHP code, the request is sent to the web server.
3. **Server Processing:**
- The web server recognizes the PHP code within the requested file. It passes the PHP code to the PHP interpreter installed on the server.
4. **PHP Interpreter:**
- The PHP interpreter processes the PHP code, executing the instructions and generating dynamic content.
5. **Server Response:**
- The server compiles the HTML output generated by PHP along with any other static content in the file.
6. **Client Receives Response:**
- The compiled HTML is sent as the server's response to the user's browser.
7. **Browser Rendering:**
- The user's browser receives the HTML response and renders the web page. From the user's perspective, the PHP code's execution is transparent; they see only the resulting HTML.
**Example: Dynamic Content Generation**
```php
<?php
$name = "John";
$greeting = "Hello, $name!";
?>
<!DOCTYPE html>
<html>
<head>
<title>Dynamic Content Example</title>
</head>
<body>
<p><?php echo $greeting; ?></p>
</body>
</html>
```
In this example, PHP dynamically generates a personalized greeting based on the value of the `$name` variable. The resulting HTML sent to the browser might look like:
```html
<!DOCTYPE html>
<html>
<head>
<title>Dynamic Content Example</title>
</head>
<body>
<p>Hello, John!</p>
</body>
</html>
```
PHP is commonly used for tasks such as database access, form handling, session management, and other server-side functionalities. Its ability to seamlessly integrate with HTML makes it a powerful tool for building dynamic and interactive web applications.