What is the purpose of the code snippet provided in the forum thread and what specific PHP function is being used?

The purpose of the code snippet provided in the forum thread is to check if a certain string contains a specific substring. The specific PHP function being used is `strpos()`, which returns the position of the first occurrence of a substring in a string, or false if the substring is not found.

// Check if the string contains a specific substring
$string = "Hello World";
$substring = "World";

if (strpos($string, $substring) !== false) {
    echo "The string contains the substring.";
} else {
    echo "The string does not contain the substring.";
}