How can session and cookie management testing help ensure application security?

Checking the field validation logic during web form testing is crucial to ensure that user inputs are properly validated and handled by the application. It helps prevent erroneous data from being submitted and ensures data integrity. Negative testing for web form input values involves testing invalid inputs to ensure that the application handles them appropriately, such as displaying error messages or rejecting the input. Session and cookie management testing plays a vital role in application security by validating the behavior of log-in sessions, testing cookie functionality, and assessing the application's response to selective cookie deletion.