What is PHP - Visual Explanation

Concept Flow - What is PHP

User requests a web page

↓

Web server receives request

↓

Server runs PHP code

↓

PHP processes data and logic

↓

PHP sends HTML output

↓

Browser displays the page

PHP runs on the web server to process code and send back HTML for the browser to show.

Execution Sample

PHP

<?php
  echo "Hello, world!";
?>

This PHP code sends the text 'Hello, world!' to the browser.

Execution Table

Step	Action	Code Executed	Output Produced
1	Start PHP script	<?php
2	Execute echo statement	echo "Hello, world!";	Hello, world!
3	End PHP script	?>

💡 PHP script ends and output is sent to browser

Variable Tracker

Variable	Start	After echo	Final
No variables	-	-	-

Key Moments - 2 Insights

Why does PHP code run on the server and not in the browser?

PHP is a server-side language, so it runs on the web server before the page is sent to the browser, as shown in the concept flow and execution table steps 1 and 3.

What does the echo statement do in PHP?

Echo sends text to the output that the browser will display, as seen in execution table step 2 where 'Hello, world!' is produced.

Visual Quiz - 3 Questions

Look at the execution table, what output is produced at step 2?

A PHP code

B No output

C Hello, world!

D Error message

💡 Hint

Check the 'Output Produced' column at step 2 in the execution table.

At which step does the PHP script end?

A Step 2

B Step 3

C Step 1

D There is no end

💡 Hint

Look at the 'Action' column for the step where PHP script ends.

If we add a variable to store 'Hello', where would it appear in the variable tracker?

A In all columns after it is set

B In the 'Start' column

C In the 'Final' column

D In the 'After echo' column

💡 Hint

Variables change over time, so track their values from start to final in the variable tracker.

Concept Snapshot

PHP is a server-side language.
It runs on the web server.
PHP code generates HTML output.
Use <?php ... ?> tags.
Echo sends output to browser.
Browser shows the final page.

Full Transcript

PHP is a programming language that runs on a web server. When a user asks for a web page, the server runs PHP code to create the page content. The PHP code can do things like show text or work with data. After running, PHP sends the result as HTML to the user's browser. The browser then shows the page. For example, the PHP code '<?php echo "Hello, world!"; ?>' sends the text 'Hello, world!' to the browser. PHP code runs step by step on the server, starting with the PHP tags, then the echo command, and finally ending the script. Variables in PHP can hold data and change as the code runs. This process helps make web pages dynamic and interactive.