How Does PHP Work With The Web Server And Browser?

Understanding PHP for Web Development

Introduction

PHP, a widely adopted server-side programming language, plays a pivotal role in powering web applications for numerous renowned companies and organizations globally. To grasp the true potential of popular frameworks like Laravel, CodeIgniter, or Symfony, as well as the inner workings of popular websites and applications, a fundamental understanding of PHP is essential. In this comprehensive guide, we will delve into the intricacies of PHP, starting with the interaction between users and web servers, and how PHP communicates with the server to deliver dynamic web content.

1. The PHP Language: An Interpretative Journey

PHP is an interpreted language, offering a distinct advantage for web development. Unlike languages such as Java or C#, where source code is compiled before execution, PHP processes code directly. When a page is requested, the PHP interpreter loads, parses, and executes the PHP code, resulting in immediate changes without the need for recompilation. PHP code is typically saved as standard text files with the .php extension, residing within a web server’s public directory.

1.1 File Structure Example

To illustrate, consider a file named index.php located in a web root directory. Users can access it through

2. PHP and Default Pages: Navigating Directory Indexes

In PHP and most web server setups, the index.php file serves as an entry point, akin to an index.html file. However, understanding the priority of these files is crucial to avoid unexpected outcomes, with index.php usually taking precedence.

3. The Request Life-cycle: Unraveling User Interaction

The journey begins when a user enters into their web browser. This initiates a GET request to the server, assuming Apache as the server of choice. Apache, upon receiving the request, searches for an index.php (or index.html) file. Once it identifies index.php, Apache recognizes it as a PHP file and delegates it to the PHP interpreter.

3.1 The Role of PHP Interpreter

PHP takes center stage by reading and executing the PHP code within the index.php file. This step may involve interactions with databases, file systems, or external API calls, among other tasks.

3.2 Return of Output

Upon completing its execution, PHP hands back the output, if any, to Apache. The web server, in turn, forwards this output to the user’s browser, resulting in the web response.

4. PHP and Apache Output: Beyond Basic HTML Generation

PHP’s primary objective is to generate HTML documents that browsers can render traditionally. However, in modern applications built with client-side MVC frameworks, PHP often transitions into a role that involves interacting with server-side data storage.

5. Conclusion: Embarking on the PHP Programming Journey

In conclusion, this introductory article provides a foundational understanding of PHP’s role in web development. Future articles in this series will explore essential topics such as variables, operators, and functions, followed by a deeper dive into Object-Oriented Programming (OOP) and its integration with PHP. By mastering these fundamentals, you’ll be well-equipped to harness the power of PHP for web applications.