In what situations would it be necessary to consider the timezone when working with date and time functions in PHP?

When working with date and time functions in PHP, it is necessary to consider the timezone when dealing with dates and times from different locations. This is important to ensure that the dates and times are accurately represented and converted across different timezones. To handle this, you can set the default timezone in your PHP script using the `date_default_timezone_set()` function to specify the timezone that all date and time functions will use.

// Set the default timezone to UTC
date_default_timezone_set('UTC');

// Now all date and time functions will use the UTC timezone
$date = date('Y-m-d H:i:s');
echo $date;