What is the significance of converting a date to a timestamp in PHP, and how can it be done using the mktime() function?

Converting a date to a timestamp in PHP is significant because timestamps are easier to work with when comparing and manipulating dates. The mktime() function in PHP allows you to convert a date to a Unix timestamp, which represents the number of seconds that have elapsed since January 1, 1970. This can be useful for tasks such as calculating the difference between two dates or sorting dates in ascending or descending order.

// Convert a date to a timestamp using mktime()
$date = "2022-12-31";
$timestamp = mktime(0, 0, 0, 12, 31, 2022);
echo $timestamp; // Output: 1672473600