PHP and HTML are two different technologies used for web development.

HTML (Hypertext Markup Language) is the standard markup language used for creating the structure and content of web pages. It consists of a series of tags that define the elements on a web page, such as headings, paragraphs, links, images, tables, forms, and more. HTML provides the basic structure and layout of a web page, and it is understood by web browsers to render the content properly.

PHP (Hypertext Preprocessor) is a server-side scripting language primarily used for web development. It is embedded within HTML code and executed on the web server before the resulting HTML is sent to the client's web browser. PHP allows dynamic generation of web pages, enabling developers to include logic, perform calculations, interact with databases, handle form submissions, and more. It provides a wide range of functions and features to build dynamic and interactive websites.

In summary, HTML is responsible for defining the structure and content of web pages, while PHP is used for server-side processing and generating dynamic web content. They often work together, with PHP code embedded within HTML files, to create dynamic and interactive websites.

Where to place PHP code in HTML?

To include PHP code within an HTML file, you need to save the file with a .php extension, indicating that it contains PHP code. Within this .php file, you can place PHP code in various locations, depending on your requirements. Here are a few common ways to include PHP code in HTML:

Inline PHP: You can insert PHP code directly within HTML tags or attributes using the opening and closing PHP tags (<?php and ?>). For example:

1	<p>Welcome <?php echo $username; ?>!</p>

In this example, the PHP code (echo $username;) is embedded within the paragraph (<p>) tag and will be evaluated and replaced with the value of the $username variable.

PHP Blocks: You can also include PHP code as separate blocks within your HTML file. You can enclose PHP code between the opening <?php tag and the closing ?> tag. For example:

<?php 
// PHP code here $currentTime = date('Y-m-d H:i:s'); 
echo "Current time is: " . $currentTime; 
?>

In this case, the PHP code is not within any specific HTML element but is a separate block that can generate output or perform server-side processing.

External PHP files: If you have larger or reusable blocks of PHP code, you can create separate PHP files and include them in your HTML file using the include or require statements. For example:

1	<?php include 'header.php'; ?>

In this example, the header.php file contains PHP code that generates the header section of your webpage. By including it using the include statement, the PHP code within header.php will be executed and inserted at that location in the HTML file.

Remember to save the file with a .php extension for the server to recognize and process the PHP code correctly. The PHP code will be executed on the server, and the resulting HTML output will be sent to the client's web browser.

What is a session in PHP? How it works

In PHP, a session is a way to store and persist data across multiple requests made by the same user. It enables the server to keep track of user-specific information throughout the user's interaction with a website or web application.

When a user visits a website, a unique session is created for that user on the server. The server generates a unique session ID, which is typically stored in a cookie on the user's browser. This session ID allows the server to associate subsequent requests from the same user with their corresponding session data.

Here's how the session works in PHP:

Session Start: At the beginning of each PHP script where you want to use sessions, you need to call the session_start() function. This function initializes or resumes an existing session for the user.
Session Data: Once the session is started, you can store and retrieve data in the session using the $_SESSION superglobal array. It acts as a container for storing session variables. For example, you can set a session variable like this:

1	$_SESSION['username'] = 'John';

Retrieving Session Data: To retrieve the stored session data, you can access the session variables in subsequent requests. For example:

1	echo $_SESSION['username']; // Outputs 'John'

Session Termination: When the user ends their session, typically by closing the browser or after a certain period of inactivity, the session is terminated automatically. PHP cleans up the session data and releases the associated resources.

It's important to note that session data is stored on the server, not on the client's browser. The session ID is typically stored as a cookie, but it can also be passed in the URL as a query parameter if cookies are disabled. The server uses this session ID to identify the correct session data for each user.

Sessions are commonly used to store user authentication information, shopping cart details, user preferences, and other user-specific data. They provide a convenient way to maintain stateful interactions with users in PHP applications.