The following data validation methods are in use: Field Level Validation - To avoid errors caused by human interaction, field level validation is performed in each field as the user enters the data. Form Level Validation - In this method, validation occurs after the user completes the form and before the information is saved. Data Saving Validation - This type of validation occurs during the actual file or database record saving process. When there are multiple data entry forms, this is usually done. Validation of Search Criteria - This type of validation is relevant to the user in that it matches what the user is looking for to some extent. Its purpose is to ensure  that the results are actually returned.