PHP is a powerful programming language used by an incredibly broad range of developers to build web backends and web applications of all sizes. The dynamically written language allows for rapid development and rollout of applications. With its intuitive syntax, vast library of functions, and compatibility with various web servers and operating systems, PHP has become a go-to choice for developers across the globe.
What is PHP?
PHP is an open-source, server-side scripting language that is primarily used for creating dynamic content on websites and has become the main language used in WordPress.
Developed in the mid-1990’s, PHP originally stood for “Personal Home Page”, however PHP has evolved over the years and now stands for the recursive acronym “Hypertext Preprocessor.”
The language is used in conjunction with HTML to create dynamic web pages and web applications. It can interact with databases such as MySQL, PostgreSQL, Oracle, Sybase, Informix, and Microsoft SQL Server to store and retrieve information. PHP can also handle session tracking, making it useful for creating e-commerce sites and other web applications that require user authentication.
PHP has simple features such as variables, functions, and arrays, and advanced features such as supporting object oriented programming (OOP), error handling, generators, and more, letting developers build complex web applications more easily. PHP has built-in logic and data handling capabilities, as well as extensions that can be added to expand its functionality.
How does PHP work?
PHP works by running on a web server, where a module or daemon called the PHP interpreter is installed. This interpreter is responsible for executing PHP code, which is then translated into an HTTP response that can be displayed in a user’s web browser.
Ongoing developments for PHP lead to the creation of the Zend engine, which is now the primary engine used to run PHP. The Zend engine is made up of several components, including; a compiler, a runtime environment, a virtual CPU and an executor. Having since become the core of the PHP language, the Zend engine is responsible for executing PHP scripts. It’s free software that can be modified and distributed by anyone.
PHP is often used with web template systems, web content management systems, and web frameworks to streamline development tasks and build complex applications quickly. It can also be used for standalone graphical applications, robotic drone control, and command line tools, making it a versatile language for a variety of projects.
PHP in the browser
Within the realm of web development, PHP serves a pivotal role in enabling seamless communication between the server and the browser. By grasping these intricacies, organizations can develop a comprehensive understanding of PHP’s functionality within the browser environment.
Request
When a user requests a web page that contains PHP code, the server receives the request. The web server recognizes that the file has a PHP extension (e.g., .php) and knows that it needs to be processed by the PHP engine.
Parsing
The PHP engine parses the PHP code, which means it examines the code line by line and understands its structure and instructions. It identifies the PHP tags (<?php … ?>) and separates them from the HTML or other non-PHP content.
Execution
Once the PHP code is parsed, the PHP engine executes it. It performs the instructions written in the PHP code, such as retrieving data from a database, performing calculations, or generating dynamic content.
“PHP serves a pivotal role in enabling seamless communication between the server and the browser.”
Interacting with the database
PHP can interact with databases to store, retrieve, and manipulate data. It uses specific functions and libraries to establish a connection with the database server, send SQL queries, and process the results. This allows PHP to fetch data from a database and use it to dynamically generate web page content.
Generating HTML
After executing the PHP code and processing any database interactions, PHP generates HTML content. HTML is the language understood by web browsers, and it defines the structure and layout of web pages. The PHP engine combines the generated HTML with any remaining static content to create a complete web page.
Response and rendering
Once the engine has generated the HTML, it sends the resulting web page as a response back to the user’s browser. The browser then receives and renders the HTML and displays it to the user, which involves interpreting the HTML structure, applying CSS styles for visual presentation, and executing any client-side JavaScript code.
PHP and WordPress
PHP is the programming language that powers WordPress, the popular content management system (CMS). WordPress and PHP form a sort of digital symbiosis in that WordPress is built using PHP, and PHP is used to create themes and plugins that add functionality and features to WordPress. The two function together in unison.
Themes in WordPress
Themes are the visual and structural templates that determine how a website looks and behaves. They are built using a combination of HTML, CSS, JavaScript, and PHP. PHP is used to generate dynamic content, such as blog posts and comments, and to create custom templates and functions that extend the functionality of WordPress.
Plugins in WordPress
Plugins, on the other hand, are pieces of software that add new features or enhance existing ones. They are also built using PHP and can be used to add anything from contact forms to eCommerce functionality to a WordPress site. Plugins can be created by anyone using PHP and then shared with the WordPress community.
Benefits of PHP for web development
Popularity
An enormous ecosystem and community has developed around PHP, meaning it is easier to build teams of developers and speeds up development due to all of the available libraries.
Platform independent
PHP does not need a specific operating system and can be used on any platform. This saves time and cost during development as it means specific teams are not needed for each platform.
Server-side rendering
When used for websites, PHP is rendered on the server side meaning initial load time is faster for the user when compared to client rendered solutions.
WordPress
WordPress is written in PHP. WordPress allows developers to create complete websites without the learning code and powers a vast amount of the web, thereby increasing the ecosystem of PHP.
Easy to learn
PHP was designed to be easy to learn. It was created to be similar to Perl and C, so existing developers could learn it rapidly. This, along with the amount of documentation available, means there are large amounts of developers who already know the language.
Flexibility
PHP allows the use of multiple libraries, databases and other languages. This flexibility and adaptability lead to a wider range of source material that developers can draw on. This speeds up development and allows the use of proven, stable components.
Criticisms of PHP: A closer look at its weaknesses
Only works on server-side
As PHP is a backend development language, it is always rendered on the server-side. Resulting static HTML is given to the browser to be displayed. This means that developers have to rely on additional JavaScript to create the front end of more interactive web applications.
Too much freedom?
It can be argued that PHP actually gives too much freedom to developers, making it easier to write poor quality code. As a result of this, it is essential for organizations to use accompanying PHP frameworks, such as Symfony or Laravel. This can increase the cost and complexity of web development.
Weak type and fewer debugging tools
PHP is a weak type language which can cause unexpected bugs during run-time. This causes an issue when paired with the fewer debugging tools available, when compared to other languages.
Not modular in design
This makes PHP harder to manage and increases the difficulty of implementing updates and fixes for large applications. Often leading to increased costs to businesses.
History of PHP
Developed in 1994 by Rasmus Lerdorf, PHP was designed as a tool for managing web forms and generating dynamic web pages. Over time, as popularity and functionality grew, PHP evolved into a full programming language with support for multiple databases.
In 1997, PHP was reportedly already used by 1% of all domains. Between 1998 and 2005, PHP continued to evolve and gain popularity among developers. In 1998, PHP 3.0 was released, which expanded on the language’s capabilities and helped further increase its popularity.
As web applications became more complex, PHP 3.0 struggled to keep pace leading to the development of the Zend Engine, which was released with PHP 4.0 in 1999. PHP 5.0 was released in 2000 on Zend Engine 2.0 to keep up with new demands from web pages.
In 2005, plans for PHP 6.0 aimed to introduce native unicode support, but the change from PHP 5.0 threatened to block many popular features, leading to a backlash from developers. As a result, PHP 6.0 was scrapped, and the reputation of PHP suffered.
Despite this setback of PHP 6.0, the language continued to grow. After 11 years of development, PHP 7.0 was released in 2015. PHP 7.0 claimed to be twice as fast as PHP 5.0 and introduced return types and changes to the syntax to include the spaceship operator.
In 2020, PHP 8.0 was released, which added the Just In Time (JIT) compiler to increase performance. PHP is now used by millions of websites and has a vibrant ecosystem of frameworks, libraries, and tools to help developers build and scalable web applications.
Longevity of PHP: Trends and ongoing development
There is an argument online that PHP is a dying development language. While this argument can carry some weight, mainly due to the introduction of multiple other programming languages since the release of PHP, it can also be claimed that the failed plans for PHP 6.0 damaged the reputation to such an extent that certain developers dislike the language to this date.
