Introduction to PHP

If HTML provides the structure of a webpage, and CSS provides the aesthetic styling, PHP provides the heavy-lifting logic that powers it behind the scenes. PHP is an acronym for PHP: Hypertext Preprocessor.

What Exactly Can PHP Do?

PHP goes far beyond what is possible with traditional HTML. As a server-side language, PHP does its work before the webpage is ever delivered to the user’s browser.

• Generate Dynamic Content: Display different information based on time of day, user location, or login status.
• Interact with Databases: Connect securely to a database to add, delete, and modify vast amounts of information.
• Form Data Collection: Securely gather passwords, emails, and files submitted by a user through web forms.
• Encryption: Safely encrypt critical user data, such as passwords, during account sign-ups.
• Access Control: Check credentials before delivering private dashboard panels restrict unauthorized internet users.

How PHP Interacts With HTML

PHP scripts are executed on the server, and the result is returned to the browser as plain HTML. You can embed PHP directly inside HTML documents using the <?php ?> tags.

Look at the unique interactive example below. It simulates how PHP replaces variables with raw text right before delivering the document wrapper to a user. Click Run and modify the $username variable to see how it affects the final structural output!

Server-Side vs. Client-Side

It’s vital to fully grasp the difference between JavaScript (Client-Side) and PHP (Server-Side).

Feature	PHP (Server-Side)	JavaScript (Client-Side)
Execution Location	Executed entirely on the web server before the page loads.	Executed almost entirely within the user’s browser after the page loads.
Visible Code	Users cannot right-click and view your raw PHP code.	Users can view your raw JS code via developer console/inspector.
Database Access	Direct and completely secure access to raw database systems.	Cannot securely connect back to core databases without relying on APIs.
Performance	Page refreshes entirely upon submitting data natively.	Manipulates elements instantly on-page without demanding page reloads (DOM).

Both languages work together beautifully in modern development: PHP generates the secured skeleton and backend data, while JavaScript polishes the frontend interactions.