$_GET for URL parameters in PHP - Step-by-Step Execution

Concept Flow - $_GET for URL parameters

User enters URL with parameters

↓

Server receives URL

↓

PHP reads $_GET array

↓

Access values by keys

↓

Use values in script

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Send response back to user

The server reads the URL parameters into the $_GET array, then the PHP script accesses these values by their keys to use in the program.

Execution Sample

PHP

<?php
$name = $_GET['name'];
echo "Hello, $name!";
?>

This code reads the 'name' parameter from the URL and prints a greeting.

Execution Table

Step	URL Parameter	$_GET Content	Action	Output
1	name=Alice	{"name" => "Alice"}	Read 'name' from $_GET
2			Assign $name = 'Alice'
3			Echo "Hello, Alice!"	Hello, Alice!
4			End of script

💡 Script ends after printing greeting using $_GET parameter

Variable Tracker

Variable	Start	After Step 2	Final
$name	undefined	'Alice'	'Alice'

Key Moments - 2 Insights

Why does $name have the value 'Alice'?

Because at Step 1, the URL parameter 'name=Alice' is read into $_GET['name'], then assigned to $name at Step 2.

What happens if the URL does not have the 'name' parameter?

Then $_GET['name'] is undefined, and trying to access it may cause a warning or error.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of $_GET after Step 1?

A {"name" => "Bob"}

B {}

C {"name" => "Alice"}

D undefined

💡 Hint

Check the '$_GET Content' column in Step 1 of the execution table.

At which step is the variable $name assigned a value?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Look at the 'Action' column to see when $name gets assigned.

If the URL parameter was 'name=Bob', what would be the output at Step 3?

A Hello, Alice!

B Hello, Bob!

C Hello, !

D Error

💡 Hint

Refer to the 'Output' column and imagine changing the URL parameter in Step 1.

Concept Snapshot

$_GET is a PHP array holding URL parameters.
Access parameters by their names as keys, e.g. $_GET['name'].
Use these values to customize output.
If parameter missing, $_GET key is undefined.
Always check if key exists to avoid errors.

Full Transcript

When a user visits a URL like example.com/page.php?name=Alice, PHP automatically fills the $_GET array with the parameters. Here, $_GET['name'] equals 'Alice'. The script reads this value and assigns it to $name. Then it prints a greeting using $name. If the parameter is missing, $_GET['name'] is not set, which can cause warnings if not handled. This process lets PHP scripts respond to user input from the URL.