What are the best practices for adding a specific number of days to a date in PHP?

When adding a specific number of days to a date in PHP, it is important to use the `DateTime` class to ensure accurate calculations, taking into account factors like leap years and daylight saving time changes. To add days to a date, you can create a `DateTime` object representing the initial date, then use the `modify()` method to add the desired number of days.

$date = new DateTime('2022-01-01');
$days_to_add = 7;
$date->modify('+' . $days_to_add . ' days');
echo $date->format('Y-m-d');