You might have come across a scenario where you need to save input from gallery control in PowerApps to SharePoint list. But how about validation of the data entered? Data entered might be wrong or blank or invalid, so how to validate such data and restrict from submitting it to backend.
When you have Form control and use SubmitForm function, validation happens automatically. But for your own controls in the gallery, you need to make use of functions like IsBlank, IsMatch etc to validate data and trace which rows are valid and which not.