What happens if a Validation Rule fails?

When a Validation Rule fails, it triggers an error message indicating the specific criteria that were not met. This prevents the record from being saved, maintaining data integrity by ensuring that only data that meets predefined standards is entered into the system. The user receives feedback about the conditions that caused the validation failure, which allows for correction. By not allowing the record to be saved, Salesforce ensures that all data adheres to the rules set forth, thus safeguarding against potential data quality issues that might arise from incorrect or incomplete data entry. This mechanism is crucial in environments where data accuracy is essential for operations or compliance purposes.