Introduction to PHP (Lesson 1)

[travis]

What is PHP?
PHP (Hypertext Preprocessor) is a server-side scripting language designed for web development. It is used to create dynamic web pages and applications that interact with databases, process user input, and generate HTML, CSS, and JavaScript code on the fly. PHP is free, open-source, cross-platform, and easy to learn, making it one of the most popular programming languages on the web.

History and Evolution of PHP
PHP was created in 1994 by Rasmus Lerdorf as a simple set of Common Gateway Interface (CGI) scripts to track visits to his personal website. Later on, he rewrote the scripts as a more powerful scripting language and released them as open-source software in 1995. PHP 2.0 was released in 1997, followed by PHP 3.0 in 1998, which introduced many new features, including support for MySQL database and dynamic content generation. PHP 4.0 was released in 2000, which brought significant performance improvements and better support for object-oriented programming. PHP 5.0 was released in 2004, which added many new features, including better support for XML and web services, improved error handling, and enhanced object-oriented programming. PHP 7.0 was released in 2015, which introduced significant performance improvements, new language features, and better support for modern web development practices.

Installing PHP
Before you can start coding in PHP, you need to install a PHP runtime environment on your computer or web server. There are several options available for installing PHP, depending on your operating system and development environment. Here are some popular options:

• XAMPP: XAMPP is a free, cross-platform, and easy-to-use web server package that includes PHP, Apache, MySQL, and other tools for web development. You can download XAMPP from the Apache Friends website and install it on your computer.
  
• WampServer: WampServer is a similar package to XAMPP that includes PHP, Apache, MySQL, and other tools for Windows users. You can download WampServer from the WampServer website and install it on your computer.
  
• MAMP: MAMP is a similar package to XAMPP that includes PHP, Apache, MySQL, and other tools for macOS users. You can download MAMP from the MAMP website and install it on your computer.
  

Writing and Running a Simple "Hello, World!" Program
Once you have installed a PHP runtime environment, you can start coding in PHP. The first program that every programmer writes is usually a "Hello, World!" program that prints a message on the screen. Here is how you can write and run a simple "Hello, World!" program in PHP:

1. Open a text editor (e.g., Notepad++, Sublime Text, or Visual Studio Code) and create a new file called "hello.php".
   
2. Type the following code in the file:
   
   Code:

   <?php echo "Hello, World!"; ?>
3. Save the file and place it in the web server's document root folder (e.g., htdocs in XAMPP).
   
4. Open a web browser and navigate to the URL of the file (e.g., http://localhost/hello.php).
   
5. The browser should display the message "Hello, World!" on the screen.
   

Explanation:

• The <?php and ?> tags indicate the start and end of a PHP code block.
  
• The echo statement is used to output text on the screen.
  
• The semicolon ( is used to indicate the end of a statement.
  

Congratulations! You have written and run your first PHP program. In the next lesson, we will learn about variables and data types in PHP.