Challenge 1 — Solution

Task: Write a script that uses session_start() and checks if
$_SESSION['visits'] exists — if not, set it to 1; if it does, increment
it by 1. Echo "You have visited this page X times." Reload the same
page (conceptually) and explain why the count keeps increasing.

<?php
    session_start();

    if (!isset($_SESSION['visits'])) {
        $_SESSION['visits'] = 1;
    } else {
        $_SESSION['visits']++;
    }

    echo "You have visited this page " . $_SESSION['visits'] . " times.";
?>


Output (first load):
You have visited this page 1 times.

Output (second load, same browser session):
You have visited this page 2 times.

Output (third load):
You have visited this page 3 times.

Notes:
- session_start() runs at the top of every request, either creating a
  brand-new session on the very first visit or resuming the existing
  one on every subsequent visit, identified by the same session cookie
  the browser keeps sending back automatically.
- Because $_SESSION data lives on the server and persists BETWEEN
  requests (unlike a plain variable, which resets to nothing on every
  new page load), $_SESSION['visits'] genuinely remembers its value
  from one reload to the next.
- The count keeps increasing because each reload is a brand-new HTTP
  request that runs this script from the top again - isset() is now
  true (the session already has a 'visits' key from the previous
  request), so the else branch runs and increments the existing value
  rather than resetting it back to 1.