What is the difference between using empty() and isset() to check if a variable is empty in PHP?

empty() in PHP checks if a variable is considered empty, which includes values such as an empty string, 0, false, null, or an empty array. isset() checks if a variable is set and is not NULL. Therefore, if you want to check if a variable is empty, you should use empty(). If you want to check if a variable is set and not NULL, you should use isset().

// Using empty() to check if a variable is empty
if (empty($variable)) {
    echo "Variable is empty";
}

// Using isset() to check if a variable is set and not NULL
if (isset($variable)) {
    echo "Variable is set and not NULL";
}