1. Hidden fields and 2. Use of URL Parameters to Pre-Fill Form Fields

The Alias ID of all your form’s fields enables you to pre-fill data into your forms when you want to via parameters in the URL. This means you automatically pre-fill data based on the activities your users do on your website and apps. The hidden field feature, enables you to get this data without annoying your users with the additional fields and long forms that they don’t want to see.

Read more details here: https://www.formaloo.com/en/how-to-use-url-parameters-to-pre-fill-form-fields/