Hidden fields can be used to include data that you already have in your form. If you have added hidden fields to your form you will be able to mention hidden field values in the same way like you would mention input fields.
Start by adding a hidden field and define your parameters (in this example 'name'). Type '@' and a dropdown will appear. Select your hidden field and the value will be inserted in your form.
Publish your form and add the parameters '?Name=value' to your URL before you share the form. All parts of the URL after the domain name are case sensitive. In this case we have added the name 'Marie' as value:
URL example: https://tally.so/r/nPd1xn?Name=Marie
When sharing the form you will see the name mentioned in the form: