What is the difference between using && and isset() function in PHP for checking variable existence?

When checking variable existence in PHP, using the && operator checks if both conditions are true, while the isset() function checks if a variable is set and is not NULL. Using isset() is a more precise way to check variable existence as it specifically checks if the variable is set, regardless of its value, while using && can lead to unexpected results if one of the conditions is not met.

// Using isset() function to check variable existence
if(isset($variable)){
    // Variable exists
    // Your code here
}