What are the best practices for formatting datetime values in PHP to meet specific visualization requirements like Highcharts?

When working with datetime values in PHP for visualization tools like Highcharts, it's important to format the dates in a way that is compatible with the charting library. One common approach is to use PHP's `date()` function to convert the datetime values into a format that Highcharts can understand, such as Unix timestamps or ISO 8601 formatted strings. This ensures that the dates are displayed correctly on the chart.

// Sample code snippet to format datetime values for Highcharts
$datetime = "2022-01-01 12:00:00";
$formatted_date = date("Y-m-d\TH:i:s", strtotime($datetime)); // Convert datetime to ISO 8601 format

echo $formatted_date; // Output: 2022-01-01T12:00:00