What is complex validation?
A validation rule may be simple or complex, based on the following criteria: Simple validation rules involve one or two simple conditions. Complex validation rules are based on validation type.
How is validation done in a form?
Form validation is a “technical process where a web-form checks if the information provided by a user is correct.” The form will either alert the user that they messed up and need to fix something to proceed, or the form will be validated and the user will be able to continue with their registration process.