What are the potential benefits and drawbacks of using sessions to track visitor activity in PHP?

Using sessions to track visitor activity in PHP can provide benefits such as allowing for personalized user experiences, tracking user behavior across multiple pages, and storing user-specific data securely. However, drawbacks may include increased server load due to storing session data, potential security risks if sessions are not properly managed, and limitations on scalability if sessions are not optimized.

// Start a session to track visitor activity
session_start();

// Store visitor activity in session variables
$_SESSION['last_activity'] = time();
$_SESSION['page_views'] = isset($_SESSION['page_views']) ? $_SESSION['page_views'] + 1 : 1;

// Retrieve and display visitor activity
echo "Last activity: " . date('Y-m-d H:i:s', $_SESSION['last_activity']);
echo "Total page views: " . $_SESSION['page_views'];