How can PHP handle time zones for displaying dates based on the user's browser time zone?

When displaying dates in PHP based on the user's browser time zone, you can use the `date_default_timezone_set()` function to set the time zone to the user's preferred time zone. This function allows you to specify the time zone using the IANA time zone database, such as "America/New_York" or "Asia/Tokyo". By setting the time zone dynamically based on the user's preferences, you can ensure that dates are displayed accurately in their local time.

// Get the user's preferred time zone from their browser
$user_timezone = $_COOKIE['user_timezone'];

// Set the default time zone to the user's preferred time zone
date_default_timezone_set($user_timezone);

// Display the current date and time in the user's time zone
echo "Current date and time: " . date("Y-m-d H:i:s");