How can the mb_substr function be utilized to correctly handle UTF-8 characters in PHP?

When working with UTF-8 characters in PHP, the `mb_substr` function should be used instead of `substr` to correctly handle multi-byte characters. This is because `substr` does not take into account the multi-byte nature of UTF-8 characters, which can lead to incorrect results such as cutting off characters in the middle. By using `mb_substr`, you ensure that the function correctly handles UTF-8 characters and returns the expected substring.

// Example of using mb_substr to correctly handle UTF-8 characters
$string = "こんにちは世界"; // UTF-8 string
$substring = mb_substr($string, 0, 5, 'UTF-8'); // Get the first 5 characters
echo $substring; // Output: こんにちは