Validation rules and page layouts are two tools that can be used to require data to be entered in a field and improve data quality on a record in Salesforce. Validation rules are a way to enforce data quality and integrity by checking the values of fields before a record is saved and displaying an error message if the values do not meet the specified criteria. Page layouts are a way to control the layout and organization of fields, buttons, related lists, and other components on a record page. Page layouts can also make fields required so that users must enter a value before saving a record.