Explains the difference between PHP's Elvis operator (?:) and null coalescing operator (??). The Elvis operator checks for truthy values and returns a fallback for any falsy value (false, 0, empty string, null), while the null coalescing operator only checks for null. Using ?? is safer when handling numeric inputs like 0, which should be preserved rather than treated as falsy. Includes practical examples with form data and user input to demonstrate when each operator is appropriate.