What are the best practices for setting the timezone in PHP scripts?

When working with PHP scripts that involve date and time functions, it's important to set the correct timezone to ensure accurate date and time calculations and display. The best practice is to set the timezone explicitly at the beginning of your script using the `date_default_timezone_set()` function and specifying the desired timezone identifier (e.g., 'America/New_York').

// Set the timezone to 'America/New_York'
date_default_timezone_set('America/New_York');