How can timestamps be used effectively in PHP to determine online user status more accurately than SessionID?

Using timestamps in PHP can be more accurate than relying solely on SessionID for determining online user status because timestamps provide a real-time indication of when a user was last active. By updating a user's timestamp each time they interact with the site, you can easily track their activity and accurately determine if they are currently online.

// Update user's timestamp when they interact with the site
$_SESSION['last_active'] = time();

// Check if user is online based on their last active timestamp
$onlineThreshold = 60; // 1 minute threshold for online status
if (isset($_SESSION['last_active']) && ($_SESSION['last_active'] + $onlineThreshold) >= time()) {
    echo "User is online";
} else {
    echo "User is offline";
}