PHP (a recursive acronym for " P HP: H hypertext P reprocessor" ) is an open-source interpreted language, primarily used in server-side (backend) web application development.

Created by Rasmus Lerdorf in 1995, PHP has development and documentation maintained by The PHP Group . PHP is distributed as open source and licensed under the PHP License .

It is estimated that between 60% and 80% of the internet is powered by applications developed in PHP. Thanks to the popularity of open source applications like WordPress and magento , PHP remains an extremely popular language, and will be for a long time to come.

What is a scripting language?

Before understanding what PHP is, we need to understand what a scripting language is.

A script is a set of programming instructions that are interpreted at runtime. Server-side scripts, such as PHP, are interpreted on the server, while client scripts are interpreted by the client application, browser, for example, as is the case with JavaScript . These languages usually depend on other applications to run, creating the execution environment.

Understanding PHP better

PHP code can be embedded in HTML code or it can be used in combination with various web template systems, web content management system and web frameworks. A PHP file contains PHP tags and ends with the ".php" extension.

<?php
  echo "Hello World";
?>

A PHP file can also contain tags like HTML and JavaScript .

<!DOCTYPE html>
<html>
  <head>
    <title>Example Page</title>
  </head>
  <body>
    <h1>
      <?php echo "Hello, I&#39;m a title!"; ?>
    </h1>
    <script>
      alert("Hello, I&#39;m an alert!");
    </script>
  </body>
</html>

Flow of a PHP application

PHP is responsible for doing all the logic for, for example, rendering a web page. It takes care of querying the databases, doing any calculations, and returning the HTML ready for the browser to display to the user.

Without getting into very technical issues, but for a web application to work you need a web server configured to run the PHP files. It is responsible for finding the correct script to run when you access a page such as https://marquesfernandes.com . The most popular and used web servers are the Apache and Nginx .

PHP in practice

Below is an example of a simple PHP code that performs a loop loop displaying HTML tags:

PHP Features

PHP is an excellent language to develop web applications, we can mention some important features:

  • Speed and robustness : With over 25 years on the market, PHP has been and is extensively tested and improved on a daily basis. It has many tutorials and courses in addition to a very active community.
  • Object orientation : PHP is a highly optimized language for object-oriented development.
  • Portability: platform independence – write once, run anywhere (or any web server you support).
  • Dynamic typing: PHP is a loosely typed language, allowing for fast and practical development.
  • Open code: You don't need to pay anything to develop or use PHP.

Extensions for a PHP file

A PHP file is saved with the extension " .php ", there are some old variations that you might be able to find in legacy applications:

  • .phtml
  • .php3
  • .php4
  • .php5
  • .phps
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