How can the use of isset() help prevent issues with undefined variables in PHP?

When working with variables in PHP, it's common to encounter undefined variable notices if a variable is accessed before it's been set. This can lead to unexpected behavior or errors in your code. Using isset() function helps prevent these issues by checking if a variable is set and not NULL before accessing its value.

// Using isset() to prevent issues with undefined variables
$variable = "Hello";
if(isset($variable)){
    echo $variable;
} else {
    echo "Variable is not set";
}