Why variables do not persist between requests in PHP

Introduction

Variables in PHP do not keep their values after a web page reloads because each request starts fresh. This helps keep things simple and secure.

When you want to understand why your data disappears after refreshing a page.

When you need to save user information between different pages.

When building login systems that remember users.

When creating shopping carts that keep items added by users.

When debugging why data is lost after submitting a form.

Syntax

PHP

<?php
// Variables are created and used inside a request
$variable = 'value';
// After the request ends, $variable is gone
?>

Each time a user visits or refreshes a page, PHP runs the script from the start.

Variables only live during that one run and then disappear.

Examples

The variable $counter resets every time, so it never remembers past values.

PHP

<?php
$counter = 1;
$counter++;
echo $counter; // Always prints 2 on each request
?>

Using sessions, PHP can remember values between requests.

PHP

<?php
session_start();
if (!isset($_SESSION['count'])) {
    $_SESSION['count'] = 0;
}
$_SESSION['count']++;
echo $_SESSION['count'];
?>

Sample Program

Every time you reload this page, it will always say "Visit number: 1" because $visits resets.

PHP

<?php
// This program shows that variables reset each request
$visits = 0;
$visits++;
echo "Visit number: $visits";
?>

Important Notes

To keep data between requests, use sessions, cookies, or databases.

Think of each request like a new conversation; variables don't remember past talks.

Summary

PHP variables only last during one page load.

After the page finishes loading, variables disappear.

Use sessions or other storage to keep data between requests.