Validation can be set up on text response fields to assure that the submitted responses adhere to a certain set of parameters. For example, if you want to assure that respondents enter a phone number, you can do so.
Validation can be implemented for:
Why is this useful?
Validation allows you to make sure you’re only collecting the responses you want, in the format you want. You can use validation to make sure you gather text responses, numerical responses, to limit the length of responses, to make sure valid email addresses are entered, etc.
Here is a video tutorial:
For more information on validation, check it out here.