Data Validation
Data Validation compares what you
type into a field and determines if it matches what you should
enter.
For example, if the field asks for a
date and you type "Michigan", there would be a mismatch.
Data validation compares data type (text
or numbers), field size, and properties.
Try It: Build an Expression
1. Create a new Text field
Field Name: eMail.
Data Type: Text.
Go to Table Tools -> Design
->Builder.
Keep going....